S-NAIL(1) BSD General Commands Manual S-NAIL(1)
NAME
S-nail [v14.9.23] -- send and receive Internet mail
SYNOPSIS
s-nail [-DdEFinv~#] [-: spec] [-A account] [:-a attachment:]
[:-b bcc-addr:] [:-C "field: body":] [:-c cc-addr:]
[-M type | -m file | -q file | -t] [-r from-addr]
[:-S var[=value]:] [-s subject] [:-T "field: addr":] [:-X cmd:]
[:-Y cmd:] [-.] :to-addr: [-- :mta-option:]
s-nail [-DdEeHiNnRv~#] [-: spec] [-A account] [:-C "field: body":]
[-L spec] [-r from-addr] [:-S var[=value]:] [-u user] [:-X cmd:]
[:-Y cmd:] [-- :mta-option:]
s-nail [-DdEeHiNnRv~#] [-: spec] [-A account] [:-C "field: body":] -f
[-L spec] [-r from-addr] [:-S var[=value]:] [:-X cmd:] [:-Y cmd:]
[file] [-- :mta-option:]
s-nail -h | --help
s-nail -V | --version
DESCRIPTION
Note: S-nail (S-nail) will see major changes in v15.0 (circa 2022).
Some backward incompatibilities cannot be avoided. COMMANDS change
to Shell-style argument quoting, and shell metacharacters will
become (more) meaningful. Some commands accept new syntax today
via wysh (Command modifiers). Behaviour is flagged [v15-compat]
and [no v15-compat], setting v15-compat (INTERNAL VARIABLES) will
choose new behaviour when applicable; giving it a value makes wysh
an implied default. [Obsolete] flags what will vanish.
Warning! v15-compat (with value) will be a default in v14.10.0!
S-nail provides a simple and friendly environment for sending and receiv-
ing mail. It is intended to provide the functionality of the POSIX
mailx(1) command, but is MIME capable and optionally offers extensions
for line editing, S/MIME, SMTP and POP3, among others. S-nail divides
incoming mail into its constituent messages and allows the user to deal
with them in any order. It offers many COMMANDS and INTERNAL VARIABLES
for manipulating messages and sending mail. It provides the user simple
editing capabilities to ease the composition of outgoing messages, and
increasingly powerful and reliable non-interactive scripting capabili-
ties.
Options
-: spec, --resource-files=..
Controls loading of (as via source) Resource files: spec is parsed
case-insensitively, the letter `s' corresponds to the system wide
s-nail.rc, `u' the user's personal file ~/.mailrc. The (original)
system wide resource is also compiled-in, accessible via `x'. The
letters `-' and `/' disable usage of resource files. Order mat-
ters, default is `su'. This option overrides -n.
-A name, --account=..
Activate user account name after program startup is complete
(resource files loaded, only -X commands are to be executed), and
switch to its primary system mailbox (most likely the inbox). If
activation fails the program exits if used non-interactively, or
if any of errexit or posix are set.
-a file[=input-charset[#output-charset]], --attach=..
(Send mode) Attach file. For (Compose mode) opportunities refer
to ~@ and ~^. file is subject to tilde expansion (see Filename
transformations and folder); if it is not accessible but contains
a `=' character, anything before the last `=' will be used as the
filename, anything thereafter as a character set specification, as
shown.
If only an input character set is specified, the input side is
fixed, and no character set conversion will be applied; an empty
or the special string hyphen-minus `-' is taken for ttycharset
(the default). If an output character set has also been specified
the desired conversion is performed immediately, not considering
file type and content, except for an empty string or hyphen-minus
`-', which select the default conversion algorithm (see Character
sets): no immediate conversion is performed, file and its contents
will be MIME-classified (HTML mail and MIME attachments, The
mime.types files) first -- only the latter mode is available
unless features includes `,+iconv,'.
-B ([Obsolete]: S-nail will always use line-buffered output, to gain
line-buffered input even in batch mode enable batch mode via -#.)
-b addr, --bcc=..
(Send mode) Send a blind carbon copy to recipient addr. The
option may be used multiple times. Also see the section On
sending mail, and non-interactive mode.
-C "field: body", --custom-header=..
Create a custom header which persists for an entire session. A
custom header consists of the field name followed by a colon `:'
and the field content body, for example `-C "Blah: Neminem laede;
imo omnes, quantum potes, juva"'. Standard header field names
cannot be overwritten by custom headers. Runtime adjustable cus-
tom headers are available via the variable customhdr, and in (Com-
pose mode) ~^, one of the COMMAND ESCAPES, as well as digmsg are
the most flexible and powerful options to manage message headers.
This option may be used multiple times.
-c addr, --cc=..
(Send mode) Just like -b, except it places the argument in the
list of carbon copies.
-D, --disconnected
[Option] Startup with disconnected set.
-d, --debug
Enter a debug-only sandbox mode by setting the internal variable
debug; the same can be achieved via `-S debug' or `set debug'.
Also see -v.
-E, --discard-empty-messages
(Send mode) set skipemptybody and thus discard messages with an
empty message part body, successfully.
-e, --check-and-exit
Just check if mail is present (in the system inbox or the one
specified via -f): if yes, return an exit status of zero, a non-
zero value otherwise. To restrict the set of mails to consider in
this evaluation a message specification can be added with the
option -L. Quickrun: does not open an interactive session.
-F (Send mode) Save the message to send in a file named after the
local part of the first recipient's address (instead of in
record).
-f, --file
Read in the contents of the user's secondary mailbox MBOX (or the
specified file) for processing; when S-nail is quit, it writes
undeleted messages back to this file (but be aware of the hold
option). The optional file argument will undergo some special
Filename transformations (as via folder). Note that file is not
an argument to the flag -f, but is instead taken from the command
line after option processing has been completed. In order to use
a file that starts with a hyphen-minus, prefix with a relative
path, as in `./-hyphenbox.mbox'.
-H, --header-summary
Display a summary of headers for the given folder (depending on
-u, inbox or MAIL, or as specified via -f), then exit. A config-
urable summary view is available via the option -L. This mode
does not honour showlast. Quickrun: does not open an interactive
session.
-h, --help
Show a brief usage summary; use --long-help for a list long
options.
-i set ignore to ignore tty interrupt signals.
-L spec, --search=..
Display a summary of headers of all messages that match the given
spec in the folder found by the same algorithm used by -H, then
exit. See the section Specifying messages for the format of spec.
This mode does not honour showlast.
If the -e option has been given in addition no header summary is
produced, but S-nail will instead indicate via its exit status
whether spec matched any messages (`0') or not (`1'); note that
any verbose output is suppressed in this mode and must instead be
enabled explicitly (see -v). Quickrun: does not open an interac-
tive session.
-M type
(Send mode) Will flag standard input with the MIME `Content-Type:'
set to the given known type (HTML mail and MIME attachments, The
mime.types files) and use it as the main message body. [v15 be-
haviour may differ] Using this option will bypass processing of
message-inject-head and message-inject-tail. Also see -q, -m, -t.
-m file
(Send mode) MIME classify the specified file and use it as the
main message body. [v15 behaviour may differ] Using this option
will bypass processing of message-inject-head and
message-inject-tail. Also see -q, -M, -t.
-N, --no-header-summary
inhibit the initial display of message headers when reading mail
or editing a mailbox folder by calling unset for the internal
variable header.
-n Standard flag that inhibits reading the system wide s-nail.rc upon
startup. The option -: allows more control over the startup
sequence; also see Resource files.
-q file, --quote-file=..
(Send mode) Initialize the message body with the contents of file,
which may be standard input `-' only in non-interactive context.
Also see -M, -m, -t.
-R, --read-only
Any mailbox folder aka folder opened will be in read-only mode.
-r from-addr, --from-address=..
The RFC 5321 reverse-path used for relaying and delegating mes-
sages to its destination(s), for example to report delivery
errors, is normally derived from the address which appears in the
from header (or, if that contains multiple addresses, in sender).
A file-based aka local executable mta (Mail-Transfer-Agent), how-
ever, instead uses the local identity of the initiating user.
When this command line option is used the given single addressee
from-addr will be assigned to the internal variable from, but in
addition the command line option -f from-addr will be passed to a
file-based mta whenever a message is sent. Shall from-addr
include a user name the address components will be separated and
the name part will be passed to a file-based mta individually via
-F name. Even though not a recipient the `shquote' expandaddr
flag is supported.
If an empty string is passed as from-addr then the content of the
variable from (or, if that contains multiple addresses, sender)
will be evaluated and used for this purpose whenever the file-
based mta is contacted. By default, without -r that is, neither
-f nor -F command line options are used when contacting a file-
based MTA, unless this automatic deduction is enforced by setting
the internal variable r-option-implicit.
Remarks: many default installations and sites disallow overriding
the local user identity like this unless either the MTA has been
configured accordingly or the user is member of a group with spe-
cial privileges. Passing an invalid address will cause an error.
-S var[=value], --set=..
set (or, with a prefix string `no', as documented in INTERNAL
VARIABLES, unset) variable and optionally assign value, if sup-
ported; [v15 behaviour may differ] the entire expression is evalu-
ated as if specified within dollar-single-quotes (see Shell-style
argument quoting) if the internal variable v15-compat is set. If
the operation fails the program will exit if any of errexit or
posix are set. Settings established via -S cannot be changed from
within Resource files or an account switch initiated by -A. They
will become mutable again before commands registered via -X are
executed.
-s subject, --subject=..
(Send mode) Specify the subject of the message to be sent. New-
line (NL) and carriage-return (CR) bytes are invalid and will be
normalized to space (SP) characters.
-T "field: addr", --target=..
(Send mode) Add addr to the list of receivers targeted by field,
for now supported are only `bcc', `cc', `fcc', and `to'. Field
and body (address) are separated by a colon `:' and optionally
blank (space, tabulator) characters. The `shquote' expandaddr
flag is supported. addr is parsed like a message header address
line, as if it would be part of a template message fed in via -t,
and the same modifier suffix is supported. This option may be
used multiple times.
-t, --template
(Send mode) The text message given (on standard input) is expected
to contain, separated from the message body by an empty line, one
or multiple plain text message headers. [v15 behaviour may dif-
fer] Readily prepared MIME mail messages cannot be passed. Head-
ers can span multiple consecutive lines if follow lines start with
any amount of whitespace. A line starting with the number sign
`#' in the first column is ignored. Message recipients can be
given via the message headers `To:', `Cc:', `Bcc:' (the `?single'
modifier enforces treatment as a single addressee, for example
`To?single: exa, <m@ple>') or `Fcc:', they will be added to any
recipients specified on the command line, and are likewise subject
to expandaddr validity checks. If a message subject is specified
via `Subject:' then it will be used in favour of one given on the
command line.
More optional headers are `Reply-To:' (possibly overriding
reply-to), `Sender:' (sender), `From:' (from and / or option -r).
`Message-ID:', `In-Reply-To:', `References:' and
`Mail-Followup-To:', by default created automatically dependent on
message context, will be used if specified (a special address mas-
sage will however still occur for the latter). Any other custom
header field (also see -C, customhdr and ~^) is passed through
entirely unchanged, and in conjunction with the options -~ or -#
it is possible to embed COMMAND ESCAPES. Also see -M, -m, -q.
-u user, --inbox-of=..
Initially read the primary system mailbox of user, appropriate
privileges presumed; effectively identical to `-f %user'.
-V, --version
Show S-nails version and exit. The command version will also show
the list of features: `$ s-nail -:/ -Xversion -Xx'.
-v, --verbose
sets the internal variable verbose to enable logging of informa-
tional context messages. (Increases level of verbosity when used
multiple times.) Also see -d.
-X cmd, --startup-cmd=..
Add the given (or multiple for a multiline argument) cmd to a list
of commands to be executed before normal operation starts. The
commands will be evaluated as a unit, just as via source. Corre-
lates with -# and errexit.
-Y cmd, --cmd=..
Add the given (or multiple for a multiline argument) cmd to a list
of commands to be executed after normal operation has started.
The commands will be evaluated successively in the given order,
and as if given on the program's standard input -- before interac-
tive prompting begins in interactive mode, after standard input
has been consumed otherwise.
-~, --enable-cmd-escapes
Enable COMMAND ESCAPES in (Compose mode) even in non-interactive
use cases. This can for example be used to automatically format
the composed message text before sending the message:
$ ( echo 'line one. Word. Word2.';\
echo '~| /usr/bin/fmt -tuw66' ) |\
LC_ALL=C s-nail -d~:/ -Sttycharset=utf-8 bob AT exam.ple
-#, --batch-mode
Enables batch mode: standard input is made line buffered, the com-
plete set of (interactive) commands is available, processing of
COMMAND ESCAPES is enabled in Compose mode, and diverse INTERNAL
VARIABLES are adjusted for batch necessities, exactly as if done
via -S: emptystart, noerrexit, noheader, noposix, quiet, sendwait,
typescript-mode as well as MAIL, MBOX and inbox (the latter three
to /dev/null). Also, the values of COLUMNS and LINES are looked
up, and acted upon. The following prepares an email message in a
batched dry run:
$ for name in bob alice AT exam.ple lisa AT exam.ple; do
printf 'mail %s\n~s ubject\nText\n~.\n' "${name}"
done |
LC_ALL=C s-nail -#:x -Smta=test \
-X'alias bob bob AT exam.ple'
-., --end-options
This flag forces termination of option processing in order to pre-
vent ``option injection'' (attacks). It also forcefully puts
S-nail into send mode, see On sending mail, and non-interactive
mode.
If the setting of expandargv allows their recognition all mta-option
arguments given at the end of the command line after a `--' separator
will be passed through to a file-based mta (Mail-Transfer-Agent) and per-
sist for the entire session. expandargv constraints do not apply to the
content of mta-arguments. Command line receiver address handling sup-
ports the `shquote' constraint of expandaddr, for more please see On
sending mail, and non-interactive mode.
$ s-nail -#:/ -X 'addrcodec enc Hey, ho <silver@go>' -Xx
A starter
S-nail is a direct descendant of BSD Mail, itself a successor to the
Research UNIX mail which ``was there from the start'' according to
HISTORY. It thus represents the user side of the UNIX mail system,
whereas the system side (Mail-Transfer-Agent, MTA) was traditionally
taken by sendmail(8) (and most MTAs provide a binary of this name for
compatibility reasons). If the [Option]al SMTP mta is included in the
features of S-nail then the system side is not a mandatory precondition
for mail delivery.
S-nail strives for compliance with the POSIX mailx(1) standard, but
posix, one of the INTERNAL VARIABLES, or its ENVIRONMENTal equivalent
POSIXLY_CORRECT, needs to be set to adjust behaviour to be almost on par.
Almost, because there is one important difference: POSIX Shell-style
argument quoting is ([v15 behaviour may differ] increasingly) used
instead of the Old-style argument quoting that the standard documents,
which is believed to be a feature. The builtin as well as the (default)
global s-nail.rc Resource files already bend the standard imposed set-
tings a bit.
For example, hold and keepsave are set in order to suppress the automatic
moving of messages to the secondary mailbox MBOX that would otherwise
occur (see Message states), and keep to not remove empty system MBOX
mailbox files (or all empty such files in posix mode) to avoid mangling
of file permissions when files eventually get recreated.
To enter interactive mode even if the initial mailbox is empty emptystart
is set, editheaders to allow editing of headers as well as fullnames to
not strip down addresses in Compose mode, and quote to include the mes-
sage that is being responded to when replying, which is indented by an
indentprefix that also deviates from standard imposed settings.
mime-counter-evidence is fully enabled, too. It sets followup-to-honour
and reply-to-honour to comply with reply address desires.
Credentials and other settings are easily addressable by grouping them
via account. The file mode creation mask can be managed with umask.
Files and shell pipe output can be sourced for evaluation, also during
startup from within the Resource files. Informational context can be
available by setting verbose or debug (as via -v, -d).
On sending mail, and non-interactive mode
To send a message to one or more people, using a local or built-in mta
(Mail-Transfer-Agent) transport to actually deliver the generated mail
message, S-nail can be invoked with arguments which are the names of peo-
ple to whom the mail will be sent, and the command line options -b and -c
can be used to add (blind) carbon copy receivers:
# Via test MTA
$ echo Hello, world | s-nail -:/ -Smta=test -s test $LOGNAME
# Via sendmail(1) MTA
$ </dev/null s-nail -:x -s test $LOGNAME
# Debug dry-run mode:
$ </dev/null LC_ALL=C s-nail -d -:/ \
-Sttycharset=utf8 -Sfullnames \
-b bcc AT exam.ple -c cc AT exam.ple -. \
'(Lovely) Bob <bob AT exam.ple>' eric AT exam.ple
# With SMTP (no real sending due to -d debug dry-run)
$ LC_ALL=C s-nail -d -:/ -Sv15-compat -Sttycharset=utf8 \
-S mta=smtps://mylogin AT exam.ple:465 -Ssmtp-auth=none \
-S from=scriptreply AT exam.ple \
-a /etc/mail.rc --end-options \
eric AT exam.ple < /tmp/letter.txt
Email addresses and plain user names are subject to alternates filtering,
names only are first expanded through alias and mta-aliases. An address
in angle brackets consisting only of a valid local user `<name>' will be
converted to a fully qualified address if either hostname is not set, or
set to a non-empty value; if set to the empty value the conversion is
left up to the mta. By setting expandaddr fine-grained control of recip-
ient address types other than user names and network addresses is possi-
ble. Recipients are classified as follows: any name that starts with a
vertical bar `|' character specifies a command pipe - the command string
following the `|' is executed and the message is sent to its standard
input; likewise, any name that consists only of hyphen-minus `-' or
starts with the character solidus `/' or the character sequence dot
solidus `./' is treated as a file, regardless of the remaining content.
Any other name which contains a commercial at `@' character is a network
address; Any other name which starts with a plus sign `+' character is a
mailbox name; Any other name which contains a solidus `/' character but
no exclamation mark `!' or percent sign `%' character before is also a
mailbox name; What remains is treated as a network address. This classi-
fication can be avoided by using a `Fcc:' header, see Compose mode.
$ echo bla | s-nail -Sexpandaddr -s test ./mbox.mbox
$ echo bla | s-nail -Sexpandaddr -s test '|cat >> ./mbox.mbox'
$ echo safe | LC_ALL=C \
s-nail -:/ -Smta=test -Sv15-compat -Sttycharset=utf8 \
--set mime-force-sendout --set fullnames \
-S expandaddr=fail,-all,+addr,failinvaddr -s test \
--end-options 'Imagine John <cold AT turk.ey>'
Before messages are sent they undergo editing in Compose mode. But many
settings are static and can be set more generally. The envelope sender
address for example is defined by from, explicitly defining an originat-
ing hostname may be desirable, especially with the built-in SMTP Mail-
Transfer-Agent mta. Character sets for outgoing message and MIME part
content are configurable via sendcharsets, whereas input data is assumed
to be in ttycharset. Message data will be passed over the wire in a
mime-encoding, and MIME parts aka attachments need a mimetype, usually
taken out of The mime.types files. Saving copies of sent messages in a
record mailbox may be desirable - as for most mailbox folder targets
Filename transformations will be performed.
For the purpose of arranging a complete environment of settings that can
be switched to with a single command or command line option there are
accounts. Alternatively a flat configuration could be possible, making
use of so-called variable chains which automatically pick `USER@HOST' or
`HOST' context-dependent variants some variables support: for example
addressing `Folder pop3://yaa AT exam.ple' would find
pop3-no-apop-yaa AT exam.ple, pop3-no-apop-exam.ple and pop3-no-apop in
order. For more please see On URL syntax and credential lookup and
INTERNAL VARIABLES.
To avoid environmental noise scripts should create a script-local envi-
ronment, ideally with the command line options -: to disable configura-
tion files in conjunction with repetitions of -S to specify variables:
$ env LC_ALL=C s-nail -:/ \
-Sv15-compat \
-Sttycharset=utf-8 -Smime-force-sendout \
-Sexpandaddr=fail,-all,failinvaddr \
-S mta=smtps://mylogin AT exam.ple:465 -Ssmtp-auth=login \
-S from=scriptreply AT exam.ple \
-s 'Subject to go' -a attachment_file \
-Sfullnames -. \
'Recipient 1 <rec1 AT exam.ple>' rec2 AT exam.ple \
< content_file
As shown, scripts producing messages can ``fake'' a locale environment,
the above specifies the all-compatible 7-bit clean LC_ALL ``C'', but will
nonetheless take and send UTF-8 in the message text by using ttycharset.
If character set conversion is compiled in (features includes the term
`,+iconv,') invalid (according to ttycharset) character input data would
normally cause errors; setting mime-force-sendout will instead, as a last
resort, classify the input as binary data, and therefore allow message
creation to be successful. (Such content can then be inspected either by
installing a pipe-TYPE/SUBTYPE handler for `application/octet-stream', or
possibly automatically through mime-counter-evidence).
In interactive mode, introduced soon, messages can be sent by calling the
mail command with a list of recipient addresses:
$ s-nail -:/ -Squiet -Semptystart -Sfullnames -Smta=test
"/var/spool/mail/user": 0 messages
? mail "Recipient 1 <rec1 AT exam.ple>", rec2 AT exam.ple
...
? # Will do the right thing (tm)
? m rec1 AT exam.ple rec2 AT exam.ple
Compose mode
If standard input is a terminal rather than the message to be sent, the
user is expected to type in the message contents. In compose mode lines
beginning with the character `~' (in fact the value of escape) are spe-
cial - these are so-called COMMAND ESCAPES which can be used to read in
files, process shell commands, add and edit attachments and more. For
example ~v or ~e will start the VISUAL text EDITOR, respectively, to
revise the message in its current state, ~h allows editing of the most
important message headers, with the potent ~^ custom headers can be cre-
ated, for example (more specifically than with -C and customhdr).
[Option]ally ~? gives an overview of most other available command
escapes.
To create file-carbon-copies the special recipient header `Fcc:' may be
used as often as desired, for example via ~^. Its entire value (or body
in standard terms) is interpreted as a folder target, after having been
subject to Filename transformations: this is the only way to create a
file-carbon-copy without introducing an ambiguity regarding the interpre-
tation of the address, file names with leading vertical bars or commer-
cial ats can be used. Like all other recipients `Fcc:' is subject to the
checks of expandaddr. Any local file and pipe command addressee honours
the setting of mbox-fcc-and-pcc.
Once finished with editing the command escape ~. (see there) will call
hooks, insert automatic injections and receivers, leave compose mode and
send the message once it is completed. Aborting letter composition is
possible with either of ~x or ~q, the latter of which will save the mes-
sage in the file denoted by DEAD unless nosave is set. And unless
ignoreeof is set the effect of ~. can also be achieved by typing end-of-
transmission (EOT) via `control-D' (`^D') at the beginning of an empty
line, and ~q is always reachable by typing end-of-text (ETX) twice via
`control-C' (`^C').
The compose mode hooks on-compose-enter, on-compose-splice,
on-compose-leave and on-compose-cleanup may be set to defined macros and
provide reliable and increasingly powerful mechanisms to perform auto-
mated message adjustments dependent on message context, for example addi-
tion of message signatures (message-inject-head, message-inject-tail) or
creation of additional receiver lists (also by setting autocc, autobcc).
To achieve that the command digmsg may be used in order to query and
adjust status of message(s). The splice hook can also make use of
COMMAND ESCAPES. ([v15 behaviour may differ] The compose mode hooks work
for forward, mail, reply and variants; resend and Resend only provide the
hooks on-resend-enter and on-resend-cleanup, which are pretty restricted
due to the nature of the operation.)
On reading mail, and more on interactive mode
When invoked without addressees S-nail enters interactive mode in which
mails may be read. When used like that the user's system inbox (for more
on mailbox types please see the command folder) is read in and a one line
header of each message therein is displayed if the variable header is
set. The visual style of this summary of headers can be adjusted through
the variable headline and the possible sorting criterion via autosort.
Scrolling through screenfuls of headers can be performed with the command
z. If the initially opened mailbox is empty S-nail will instead exit
immediately (after displaying a message) unless the variable emptystart
is set.
At the prompt the command list will give a listing of all available com-
mands and help will [Option]ally give a summary of some common ones. If
the [Option]al documentation strings are available (see features) one can
type `help X' (or `?X') and see the actual expansion of `X' and what its
purpose is, i.e., commands can be abbreviated (note that POSIX defines
some abbreviations, so that the alphabetical order of commands does not
necessarily relate to the abbreviations; it is however possible to define
overwrites with commandalias). These commands can also produce a more
verbose output.
Messages are given numbers (starting at 1) which uniquely identify mes-
sages; the current message - the ``dot'' - will either be the first new
message, or the first unread message, or the first message of the mail-
box; the internal variable showlast will instead cause usage of the last
message for this purpose. The command headers will display a screenful
of header summaries containing the ``dot'', whereas from will display
only the summaries of the given messages, defaulting to the ``dot''.
Message content can be displayed with the command type (`t', alias
print). Here the variable crt controls whether and when S-nail will use
the configured PAGER for display instead of directly writing to the user
terminal screen, the sole difference to the command more, which will
always use the PAGER. The command top will instead only show the first
toplines of a message (maybe even compressed if topsqueeze is set). Mes-
sage display experience may improve by setting and adjusting
mime-counter-evidence, and also see HTML mail and MIME attachments.
By default the current message (``dot'') is displayed, but like with many
other commands it is possible to give a fancy message specification (see
Specifying messages), for example `t:u' will display all unread messages,
`t.' will display the ``dot'', `t 1 5' will type the messages 1 and 5, `t
1-5' will type the messages 1 through 5, and `t-' and `t+' will display
the previous and the next message, respectively. The command search (a
more substantial alias for from) will display a header summary of the
given message specification list instead of their content; the following
will search for subjects:
? from '@Some subject to search for'
In the default setup all header fields of a message will be typed, but
fields can be white- or blacklisted for a variety of applications by
using the command headerpick, e.g., to restrict their display to a very
restricted set for type: `headerpick type retain from to cc subject'. In
order to display all header fields of a message regardless of currently
active ignore or retain lists, use the commands Type and Top; Show will
show the raw message content. Note that historically the global
s-nail.rc not only adjusts the list of displayed headers, but also sets
crt. ([v15 behaviour may differ] A yet somewhat restricted) Reliable
scriptable message inspection is available via digmsg.
Dependent upon the configuration a line editor (see the section On
terminal control and line editor) aims at making the user experience with
the many COMMANDS a bit nicer. When reading the system inbox, or when -f
(or folder) specified a mailbox explicitly prefixed with the special `%:'
modifier (to propagate it to a primary system mailbox), then messages
which have been read (see Message states) will be automatically moved to
a secondary mailbox, the user's MBOX file, when the mailbox is left,
either by changing the active mailbox or by quitting S-nail - this auto-
matic moving from a system- or primary- to the secondary mailbox is not
performed when the variable hold is set. Messages can also be explicitly
moved to other mailboxes, whereas copy keeps the original message. write
can be used to write out data content of specific parts of messages.
After examining a message the user can reply `r' to the sender and all
recipients (which will also be placed in `To:' unless recipients-in-cc is
set), or Reply `R' exclusively to the sender(s). To comply with with the
receivers desired reply address the quadoptions followup-to-honour and
reply-to-honour should usually be set. The commands Lreply and Lfollowup
know how to apply a special addressee massage, see Mailing lists. Depen-
dent on the presence and value of quote the message being replied to will
be included in a quoted form. forwarding a message will allow editing
the new message: the original message will be contained in the message
body, adjusted according to headerpick. It is possible to resend or
Resend messages: the former will add a series of `Resent-' headers,
whereas the latter will not; different to newly created messages editing
is not possible and no copy will be saved even with record unless the
additional variable record-resent is set. When sending, replying or for-
warding messages comments and full names will be stripped from recipient
addresses unless the internal variable fullnames is set.
Of course messages can be delete `d', and they can spring into existence
again via undelete, or when the S-nail session is ended via the exit or
xit commands to perform a quick program termation. To end a mail pro-
cessing session regularly and perform a full program exit one may issue
the command quit. It will, among others, move read messages to the
secondary mailbox MBOX as necessary, discard deleted messages in the cur-
rent mailbox, and update the [Option]al (see features) line editor
history-file. By the way, whenever the main event loop is about to look
out for the next input line it will trigger the hook on-main-loop-tick.
HTML mail and MIME attachments
HTML-only messages become more and more common, and many messages come
bundled with a bouquet of MIME (Multipurpose Internet Mail Extensions)
parts and attachments. To get a notion of MIME types there is a built-in
default set, onto which the content of The mime.types files will be added
(as configured and allowed by mimetypes-load-control). Types can also
become registered and listed with the command mimetype. To improve
interaction with the faulty MIME part declarations of real life
mime-counter-evidence will allow verification of the given assertion, and
the possible provision of an alternative, better MIME type. Note plain
text parts will always be preferred in `multipart/alternative' MIME mes-
sages unless mime-alternative-favour-rich is set.
Whereas a simple HTML-to-text filter for displaying HTML messages is
[Option]ally supported (indicated by `,+filter-html-tagsoup,' in
features), MIME types other than plain text cannot be handled directly.
To deal with specific non-text MIME types or file extensions programs
need to be registered which either prepare (re-)integrable plain text
versions of their input (a mode which is called copiousoutput), or dis-
play the content externally, for example in a graphical window: the lat-
ter type is only considered by and for the command mimeview.
To install a handler program for a MIME type an according
pipe-TYPE/SUBTYPE variable needs to be set; to define a handler for a
file extension pipe-EXTENSION can be used - these handlers take prece-
dence. [Option]ally mail user agent configuration is supported (see The
Mailcap files), and will be queried for display or quote handlers after
the former ones. Type-markers registered via mimetype are the last pos-
sible source for information how to handle a MIME type.
For example, to display HTML messages integrated via the text browsers
lynx(1) or elinks(1), register a MathML MIME type and enable its plain
text display, and to open PDF attachments in an external PDF viewer,
asynchronously and with some other magic attached:
? if "$features" !% ,+filter-html-tagsoup,
? #set pipe-text/html='?* elinks -force-html -dump 1'
? set pipe-text/html='?* lynx -stdin -dump -force_html'
? # Display HTML as plain text instead
? #set pipe-text/html=?t
? endif
? mimetype ?t application/mathml+xml mathml
? wysh set pipe-application/pdf='?&=? \
trap "rm -f \"${MAILX_FILENAME_TEMPORARY}\"" EXIT;\
trap "trap \"\" INT QUIT TERM; exit 1" INT QUIT TERM;\
mupdf "${MAILX_FILENAME_TEMPORARY}"'
? define showhtml {
? \localopts yes
? \set mime-alternative-favour-rich pipe-text/html=?h?
? \type "$@"
? }
? \commandalias html \\call showhtml
Mailing lists
Known or subscribed-to mailing lists may be flagged in the summary of
headers (headline format character `%L'), and will gain special treatment
when sending mails: the variable followup-to-honour will ensure that a
`Mail-Followup-To:' header is honoured when a message is being replied to
(reply, followup, Lreply, Lfollowup), and followup-to controls creation
of this header when creating mails, if the necessary user setup (from,
sender); is available; then, it may also be created automatically, for
example when list-replying via Lreply or Lfollowup, when followup or
reply is used and the messages `Mail-Followup-To:' is honoured etc.
The commands mlist and mlsubscribe manage S-nails notion of which
addresses are mailing lists. With the [Option]al regular expression sup-
port any address which contains any of the magic regular expression char-
acters (`^[*+?|$'; see re_format(7) or regex(7), dependent on the host
system) will be compiled and used as one, possibly matching many
addresses. It is not possible to escape the ``magic'': in order to match
special characters as-is, bracket expressions must be used, for example
`search @subject@'[[]open bracket''.
? set followup-to followup-to-honour=ask-yes \
reply-to-honour=ask-yes
? mlist a1 AT b1.c1 a2 AT b2.c2 '.*@lists\.c3$'
? mlsubscribe a4 AT b4.c4 exact AT lists.c3
Known and subscribed lists differ in that for the latter the users
address is not part of a generated `Mail-Followup-To:'. There are excep-
tions, for example if multiple lists are addressed and not all have the
subscription attribute. When replying to a message its list address
(`List-Post:' header) is automatically and temporarily treated like a
known mlist; dependent on the variable reply-to-honour an existing
`Reply-To:' is used instead (if it is a single address on the same domain
as `List-Post:') in order to accept a list administrator's wish that is
supposed to have been manifested like that.
For convenience and compatibility with mail programs that do not honour
the non-standard M-F-T, an automatic user entry in the carbon-copy `Cc:'
address list of generated message can be created by setting
followup-to-add-cc. This entry will be added whenever the user will be
placed in the `Mail-Followup-To:' list, and is not a regular addressee
already. reply-to-swap-in tries to deal with the address rewriting that
many mailing-lists nowadays perform to work around DKIM / DMARC etc.
standard imposed problems.
Signed and encrypted messages with S/MIME
[Option] S/MIME provides two central mechanisms: message signing and mes-
sage encryption. A signed message contains some data in addition to the
regular text. The data can be used to verify that the message has been
sent using a valid certificate, that the sender address matches that in
the certificate, and that the message text has not been altered. Signing
a message does not change its regular text; it can be read regardless of
whether the recipients software is able to handle S/MIME. It is thus
usually possible to sign all outgoing messages if so desired.
Encryption, in contrast, makes the message text invisible for all people
except those who have access to the secret decryption key. To encrypt a
message, the specific recipients public encryption key must be known. It
is therefore not possible to send encrypted mail to people unless their
key has been retrieved from either previous communication or public key
directories. Because signing is performed with private keys, and encryp-
tion with public keys, messages should always be signed before being
encrypted.
A central concept to S/MIME is that of the certification authority (CA).
A CA is a trusted institution that issues certificates. For each of
these certificates it can be verified that it really originates from the
CA, provided that the CA's own certificate is previously known. A set of
CA certificates is usually delivered and installed together with the
cryptographical library that is used on the local system. Therefore rea-
sonable security for S/MIME on the Internet is provided if the source
that provides that library installation is trusted. It is also possible
to use a specific pool of trusted certificates. If this is desired,
smime-ca-no-defaults should be set to avoid using the default certificate
pool, and smime-ca-file and/or smime-ca-dir should be pointed to a
trusted pool of certificates. A certificate cannot be more secure than
the method its CA certificate has been retrieved with.
This trusted pool of certificates is used by the command verify to ensure
that the given S/MIME messages can be trusted. If so, verified sender
certificates that were embedded in signed messages can be saved locally
with the command certsave, and used by S-nail to encrypt further communi-
cation with these senders:
? certsave FILENAME
? set smime-encrypt-USER@HOST=FILENAME \
smime-cipher-USER@HOST=AES256
To sign outgoing messages, in order to allow receivers to verify the ori-
gin of these messages, a personal S/MIME certificate is required. S-nail
supports password-protected personal certificates (and keys), see
smime-sign-cert. The section On URL syntax and credential lookup gives
an overview of the possible sources of user credentials, and S/MIME step
by step shows examplarily how a private S/MIME certificate can be
obtained. In general, if such a private key plus certificate ``pair'' is
available, all that needs to be done is to set some variables:
? set smime-sign-cert=ME AT exam.paired \
smime-sign-digest=SHA512 \
smime-sign from=myname AT my.host
Variables of interest for S/MIME in general are smime-ca-dir,
smime-ca-file, smime-ca-flags, smime-ca-no-defaults, smime-crl-dir,
smime-crl-file. For S/MIME signing of interest are smime-sign,
smime-sign-cert, smime-sign-include-certs and smime-sign-digest. Addi-
tional variables of interest for S/MIME en- and decryption: smime-cipher
and smime-encrypt-USER@HOST. Variables of secondary interest may be
content-description-smime-message and
content-description-smime-signature. S/MIME is available if `,+smime,'
is included in features.
[v15 behaviour may differ] Note that neither S/MIME signing nor encryp-
tion applies to message subjects or other header fields yet. Thus they
may not contain sensitive information for encrypted messages, and cannot
be trusted even if the message content has been verified. When sending
signed messages, it is recommended to repeat any important header infor-
mation in the message text.
On URL syntax and credential lookup
For accessing protocol-specific resources Uniform Resource Locators (URL,
RFC 3986) have become omnipresent. Here they are expected in a
``normalized'' variant, not used in data exchange, but only meant as a
compact, easy-to-use way of defining and representing information in a
well-known notation; as such they do not conform to any real standard.
Optional parts are placed in brackets `[]', optional either because there
also exist other ways to define the information, or because the part is
protocol specific. `/path' for example is used by the [Option]al Maildir
folder type and the IMAP protocol, but not by POP3. If `USER' and
`PASSWORD' are included in an URL server specification, URL percent
encoded (RFC 3986) forms are needed, generable with urlcodec.
PROTOCOL://[USER[:PASSWORD]@]server[:port][/path]
Often INTERNAL VARIABLES exist in multiple versions, called ``variable
chains'' in this document: the plain `variable' as well as
`variable-HOST' and `variable-USER@HOST'. If a port was specified `HOST'
really means `server:port', not `server'. And this `USER' is never in
URL percent encoded form. For example, whether the hypothetical `smtp://
wings%3Aof AT a.dove' including user and password was used, or whether it
was `smtp://a.dove' and it came from a different source, to lookup the
chain tls-config-pairs first `tls-config-pairs-wings:of AT a.dove' is looked
up, then `tls-config-pairs-a.dove', before finally looking up the plain
variable.
The logic to collect (an accounts) credential information is as follows:
o A user is always required. If no `USER' has been given in the URL
the variables user-HOST and user are looked up. Afterwards, when
enforced by the [Option]al variables netrc-lookup-HOST or
netrc-lookup, The .netrc file of the user will be searched for a
`HOST' specific entry which provides a `login' name: only unambiguous
entries are used (one possible matching entry for `HOST').
If there is still no `USER' then the verified LOGNAME, known to be a
valid user on the current host, is used.
o Authentication: unless otherwise noted the chain
PROTOCOL-auth-USER@HOST, PROTOCOL-auth-HOST, PROTOCOL-auth is
checked, falling back to a protocol-specific default as necessary.
o If no `PASSWORD' has been given in the URL, then if the `USER' has
been found through the [Option]al netrc-lookup, that may have also
provided the password. Otherwise the chain password-USER@HOST,
password-HOST, password is looked up.
Thereafter the (now complete) [Option]al chain
netrc-lookup-USER@HOST, netrc-lookup-HOST, netrc-lookup is checked,
if set the netrc cache is searched for a password only (multiple user
accounts for a single machine may exist as well as a fallback entry
without user but with a password).
If at that point there is still no password available, but the (pro-
tocols') chosen authentication type requires a password, then in
interactive mode the user will be prompted on the terminal.
Note: S/MIME verification works relative to the values found in the
`From:' (or `Sender:') header field(s), which means the values of
smime-sign, smime-sign-cert, smime-sign-include-certs and
smime-sign-digest will not be looked up using the `USER' and `HOST'
chains from above, but instead use the corresponding values from the mes-
sage that is being worked on. If no address matches we assume and use
the setting of from. In unusual cases multiple and different `USER' and
`HOST' combinations may therefore be involved - on the other hand those
unusual cases become possible. The usual case is as short as:
set mta=smtp://USER:PASS@HOST smtp-use-starttls \
smime-sign smime-sign-cert=+smime.pair \
from=myname AT my.host
The section EXAMPLES contains complete example configurations.
Encrypted network communication
[Option] SSL (Secure Sockets Layer) aka its successor TLS (Transport
Layer Security) are protocols which aid in securing communication by pro-
viding a safely initiated and encrypted network connection. A central
concept of TLS are certificates: as part of each network connection setup
a (set of) certificates will be exchanged through which the identity of
the network peer can be cryptographically verified; if possible the
TLS/SNI (ServerNameIndication) extension will be enabled to allow servers
fine-grained control over the certificates being used. A locally
installed pool of trusted certificates will then be inspected, and veri-
fication will succeed if it contains a(n in)direct signer of the pre-
sented certificate(s).
The local pool of trusted so-called CA (Certification Authority) certifi-
cates is usually delivered with and used along the TLS library. A custom
pool of trusted certificates can be selected by pointing tls-ca-file
and/or (with special preparation) tls-ca-dir to the desired location;
setting tls-ca-no-defaults in addition will avoid additional inspection
of the default pool. A certificate cannot be more secure than the method
its CA certificate has been retrieved with. For inspection or other pur-
poses, the certificate of a server (as seen when connecting to it) can be
fetched with the command tls (port can usually be the protocol name, too,
and tls-verify is taken into account here):
$ s-nail -vX 'tls certchain SERVER-URL[:PORT]; x'
A local pool of CA certificates is not strictly necessary, however,
server certificates can also be verified via their fingerprint. For this
a message digest will be calculated and compared against the variable
chain tls-fingerprint, and verification will succeed if the fingerprint
matches. The message digest (algorithm) can be configured via the vari-
able chain tls-fingerprint-digest; tls can again be used:
$ s-nail -X 'wysh set verbose; tls fingerprint SERVER-URL[:PORT]; x'
It depends on the used protocol whether encrypted communication is possi-
ble, and which configuration steps have to be taken to enable it. Some
protocols, like POP3S, are implicitly encrypted, others, like POP3, can
upgrade a plain text connection if so requested. For example, to use the
`STLS' that POP3 offers (a member of) the variable (chain)
pop3-use-starttls needs to be set, with convenience via shortcut:
shortcut encpop1 pop3s://pop1.exam.ple
shortcut encpop2 pop3://pop2.exam.ple
set pop3-use-starttls-pop2.exam.ple
set mta=smtps://smtp.exam.ple:465
set mta=smtp://smtp.exam.ple smtp-use-starttls
Normally that is all there is to do, given that TLS libraries try to pro-
vide safe defaults, plenty of knobs however exist to adjust settings.
For example certificate verification settings can be fine-tuned via
tls-ca-flags, and the TLS configuration basics are accessible via
tls-config-pairs, for example to control protocol versions or cipher
lists. In the past hints on how to restrict the set of protocols to
highly secure ones were indicated, but as of the time of this writing the
list of protocols or ciphers may need to become relaxed in order to be
able to connect to some servers; the following example allows connecting
to a ``Lion'' that uses OpenSSL 0.9.8za from June 2014 (refer to INTERNAL
VARIABLES for more on variable chains):
wysh set tls-config-pairs-lion AT exam.ple='MinProtocol=TLSv1.1,\
CipherString=TLSv1.2:!aNULL:!eNULL:\
ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:\
DHE-RSA-AES256-SHA:@STRENGTH'
The OpenSSL program ciphers(1) should be referred to when creating a cus-
tom cipher list. Variables of interest for TLS in general are
tls-ca-dir, tls-ca-file, tls-ca-flags, tls-ca-no-defaults,
tls-config-file, tls-config-module, tls-config-pairs, tls-crl-dir,
tls-crl-file, tls-rand-file as well as tls-verify. Also see
tls-features. TLS is available if `+tls' is included in features.
Character sets
[Option] The user's locale environment is detected by looking at the
LC_ALL environment variable. The internal variable ttycharset will be
set to the detected terminal character set accordingly, and will thus
show up in the output of commands like set and varshow. This character
set will be targeted when trying to display data, and user input data is
expected to be in this character set, too.
When creating messages their character input data is classified. 7-bit
clean text data and attachments will be classified as charset-7bit.
8-bit data will [Option]ally be converted into members of sendcharsets
until a character set conversion succeeds. charset-8bit is the implied
default last member of this list. If no 8-bit character set is capable
to represent input data, no message will be sent, and its text will
optionally be saved in DEAD. If that is not acceptable, for example in
script environments, mime-force-sendout can be set to force sending of
non-convertible data as `application/octet-stream' classified binary con-
tent instead: like this receivers still have the option to inspect mes-
sage content (for example via mime-counter-evidence). If the [Option]al
character set conversion is not available (features misses `,+iconv,'),
ttycharset is the only supported character set for non 7-bit clean data,
and it is simply assumed it can be used to exchange 8-bit messages.
ttycharset may also be given an explicit value to send mail in a com-
pletely ``faked'' locale environment, which can be used to generate and
send for example 8-bit UTF-8 input data in a pure 7-bit US-ASCII
`LC_ALL=C' environment (an example of this can be found in the section On
sending mail, and non-interactive mode). Due to lack of programming
interfaces reading mail will not really work as expected in a faked envi-
ronment: whereas ttycharset might be addressable, any output will be made
safely printable, as via vexpr makeprint, according to the actual locale
environment, which is not affected by ttycharset.
Classifying 7-bit clean data as charset-7bit is a problem if the input
character set (ttycharset) is a multibyte character set that is itself
7-bit clean. For example, the Japanese character set ISO-2022-JP is, but
is capable to encode the rich set of Japanese Kanji, Hiragana and
Katakana characters: in order to notify receivers of this character set
the mail message must be MIME encoded so that the character set
ISO-2022-JP can be advertised, otherwise an invalid email message would
result! To achieve this, the variable charset-7bit can be set to
ISO-2022-JP. (Today a better approach regarding email is the usage of
UTF-8, which uses 8-bit bytes for non-US-ASCII data.)
When replying to a message and the variable reply-in-same-charset is set,
the character set of the message being replied to is tried first as a
target character set (still being a subject of charsetalias filtering,
however). Another opportunity is sendcharsets-else-ttycharset to reflect
the user's locale environment automatically, it will treat ttycharset as
an implied member of (an unset) sendcharsets.
[Option] When reading messages, their text data is converted into
ttycharset as necessary in order to display them on the user's terminal.
Unprintable characters and invalid byte sequences are detected and
replaced by substitution characters. Character set mappings for source
character sets can be established with charsetalias, which may be handy
to work around faulty or incomplete character set catalogues (one could
for example add a missing LATIN1 to ISO-8859-1 mapping), or to enforce
treatment of one character set as another one (``interpret LATIN1 as
CP1252''). Also see charset-unknown-8bit to deal with another hairy
aspect of message interpretation.
In general, if a message saying ``cannot convert from a to b'' appears,
either some characters are not appropriate for the currently selected
(terminal) character set, or the needed conversion is not supported by
the system. In the first case, it is necessary to set an appropriate
LC_CTYPE locale and/or the variable ttycharset. The best results are
usually achieved when running in a UTF-8 locale on a UTF-8 capable termi-
nal, in which case the full Unicode spectrum of characters is available.
In this setup characters from various countries can be displayed, while
it is still possible to use more simple character sets for sending to
retain maximum compatibility with older mail clients.
On the other hand the POSIX standard defines a locale-independent 7-bit
``portable character set'' that should be used when overall portability
is an issue, the even more restricted subset named ``portable filename
character set'' consists of A-Z, a-z, 0-9, period `.', underscore `_' and
hyphen-minus `-'.
Message states
S-nail differentiates in between several message states; the current
state will be reflected in the summary of headers if the attrlist of the
configured headline allows, and Specifying messages dependent on their
state is possible. When operating on the system inbox, or in any other
primary system mailbox, special actions, like the automatic moving of
messages to the secondary mailbox MBOX, may be applied when the mailbox
is left (also implicitly by program termination, unless the command exit
was used) - however, because this may be irritating to users which are
used to ``more modern'' mail-user-agents, the provided global s-nail.rc
template sets the internal hold and keepsave variables in order to sup-
press this behaviour.
`new' Message has neither been viewed nor moved to any other state.
Such messages are retained even in the primary system mailbox.
`unread' Message has neither been viewed nor moved to any other state,
but the message was present already when the mailbox has been
opened last: Such messages are retained even in the primary
system mailbox.
`read' The message has been processed by one of the following com-
mands: ~f, ~m, ~F, ~M, copy, mbox, next, pipe, Print, print,
top, Type, type, undelete. The commands dp and dt will always
try to automatically ``step'' and type the ``next'' logical
message, and may thus mark multiple messages as read, the
delete command will do so if the internal variable autoprint is
set.
Except when the exit command is used, messages that are in a
primary system mailbox and are in `read' state when the mailbox
is left will be saved in the secondary mailbox MBOX unless the
internal variable hold it set.
`deleted' The message has been processed by one of the following com-
mands: delete, dp, dt. Only undelete can be used to access
such messages.
`preserved' The message has been processed by a preserve command and it
will be retained in its current location.
`saved' The message has been processed by one of the following com-
mands: save or write. Unless when the exit command is used,
messages that are in a primary system mailbox and are in
`saved' state when the mailbox is left will be deleted; they
will be saved in the secondary mailbox MBOX when the internal
variable keepsave is set.
In addition to these message states, flags which otherwise have no tech-
nical meaning in the mail system except allowing special ways of address-
ing them when Specifying messages can be set on messages. These flags
are saved with messages and are thus persistent, and are portable between
a set of widely used MUAs.
answered Mark messages as having been answered.
draft Mark messages as being a draft.
flag Mark messages which need special attention.
Specifying messages
[Only new quoting rules] COMMANDS which take Message list arguments, such
as search, type, copy, and delete, can perform actions on a number of
messages at once. Specifying invalid messages, or using illegal syntax,
will cause errors to be reported through the INTERNAL VARIABLES !, ^ERR
and companions, as well as the command exit status ?.
For example, `delete 1 2' deletes the messages 1 and 2, whereas `delete
1-5' will delete the messages 1 through 5. In sorted or threaded mode
(see the sort command), `delete 1-5' will delete the messages that are
located between (and including) messages 1 through 5 in the
sorted/threaded order, as shown in the headers summary.
Errors can for example be ^ERR-BADMSG when requesting an invalid message,
^ERR-NOMSG if no applicable message can be found, ^ERR-CANCELED for miss-
ing informational data (mostly thread-related). ^ERR-INVAL for invalid
syntax as well as ^ERR-IO for input/output errors can happen. The fol-
lowing special message names exist:
. The current message, the so-called ``dot''.
; The message that was previously the current message; needs to be
quoted.
, The parent message of the current message, that is the message with
the Message-ID given in the `In-Reply-To:' field or the last entry
of the `References:' field of the current message.
- The previous undeleted message, or the previous deleted message for
the undelete command; In sorted or `thread'ed mode, the previous
such message in the according order.
+ The next undeleted message, or the next deleted message for the
undelete command; In sorted or `thread'ed mode, the next such mes-
sage in the according order.
^ The first undeleted message, or the first deleted message for the
undelete command; In sorted or `thread'ed mode, the first such mes-
sage in the according order.
$ The last message; In sorted or `thread'ed mode, the last such mes-
sage in the according order. Needs to be quoted.
&x In `thread'ed sort mode, selects the message addressed with x,
where x is any other message specification, and all messages from
the thread that begins at it. Otherwise it is identical to x. If
x is omitted, the thread beginning with the current message is
selected.
* All messages.
` All messages that were included in the Message list arguments of
the previous command; needs to be quoted. (A convenient way to
read all new messages is to select them via `from :n', as below,
and then to read them in order with the default command -- next --
simply by successively typing ``'; for this to work showlast must
be set.)
x-y An inclusive range of message numbers. Selectors that may also be
used as endpoints include any of .;-+^$.
address
A case-insensitive ``any substring matches'' search against the
`From:' header, which will match addresses (too) even if showname
is set (and POSIX says ``any address as shown in a header summary
shall be matchable in this form''); However, if the allnet variable
is set, only the local part of the address is evaluated for the
comparison, not ignoring case, and the setting of showname is com-
pletely ignored. For finer control and match boundaries use the
`@' search expression.
/string
All messages that contain string in the subject field (case ignored
according to locale). See also the searchheaders variable. If
string is empty, the string from the previous specification of that
type is used again.
[@name-list]@expr
All messages that contain the given case-insensitive search
expression; If the [Option]al regular expression support is avail-
able expr will be interpreted as (an extended) one if any of the
magic regular expression characters is seen. If the optional
@name-list part is missing the search is restricted to the subject
field body, but otherwise name-list specifies a comma-separated
list of header fields to search, for example
'@to,from,cc@Someone i ought to know'
In order to search for a string that includes a `@' (commercial at)
character the name-list is effectively non-optional, but may be
given as the empty string. Also, specifying an empty search
expression will effectively test for existence of the given header
fields. Some special header fields may be abbreviated: `f', `t',
`c', `b' and `s' will match `From', `To', `Cc', `Bcc' and
`Subject', respectively and case-insensitively. [Option]ally, and
just like expr, name-list will be interpreted as (an extended) reg-
ular expression if any of the magic regular expression characters
is seen.
The special names `header' or `<' can be used to search in (all of)
the header(s) of the message, and the special names `body' or `>'
and `text' or `=' will perform full text searches - whereas the
former searches only the body, the latter also searches the message
header ([v15 behaviour may differ] this mode yet brute force
searches over the entire decoded content of messages, including
administrativa strings).
This specification performs full text comparison, but even with
regular expression support it is almost impossible to write a
search expression that safely matches only a specific address
domain. To request that the body content of the header is treated
as a list of addresses, and to strip those down to the plain email
address which the search expression is to be matched against, pre-
fix the effective name-list with a tilde `~':
'@~f,c@@a\.safe\.domain\.match$'
:c All messages of state or with matching condition `c', where `c' is
one or multiple of the following colon modifiers:
a answered messages (cf. the variable markanswered).
d `deleted' messages (for the undelete and from commands only).
f flagged messages.
L Messages with receivers that match mlsubscribed addresses.
l Messages with receivers that match mlisted addresses.
n `new' messages.
o Old messages (any not in state `read' or `new').
r `read' messages.
S [Option] Messages with unsure spam classification (see Handling
spam).
s [Option] Messages classified as spam.
t Messages marked as draft.
u `unread' messages.
[Option] IMAP-style SEARCH expressions may also be used. These consist
of keywords and criterions, and because Message list arguments are split
into tokens according to Shell-style argument quoting it is necessary to
quote the entire IMAP search expression in order to ensure that it
remains a single token. This addressing mode is available with all types
of mailbox folders; S-nail will perform the search locally as necessary.
Strings must be enclosed by double quotation marks `"' in their entirety
if they contain whitespace or parentheses; within the quotes, only
reverse solidus `\' is recognized as an escape character. All string
searches are case-insensitive. When the description indicates that the
``envelope'' representation of an address field is used, this means that
the search string is checked against both a list constructed as
'("name" "source" "local-part" "domain-part")'
for each address, and the addresses without real names from the respec-
tive header field. These search expressions can be nested using paren-
theses, see below for examples.
(criterion)
All messages that satisfy the given criterion.
(criterion1 criterion2 ... criterionN)
All messages that satisfy all of the given criteria.
(or criterion1 criterion2)
All messages that satisfy either criterion1 or criterion2, or both.
To connect more than two criteria using `or' specifications have to
be nested using additional parentheses, as with `(or a (or b c))',
since `(or a b c)' really means `((a or b) and c)'. For a simple
`or' operation of independent criteria on the lowest nesting level,
it is possible to achieve similar effects by using three separate
criteria, as with `(a) (b) (c)'.
(not criterion)
All messages that do not satisfy criterion.
(bcc "string")
All messages that contain string in the envelope representation of
the `Bcc:' field.
(cc "string")
All messages that contain string in the envelope representation of
the `Cc:' field.
(from "string")
All messages that contain string in the envelope representation of
the `From:' field.
(subject "string")
All messages that contain string in the `Subject:' field.
(to "string")
All messages that contain string in the envelope representation of
the `To:' field.
(header name "string")
All messages that contain string in the specified `Name:' field.
(body "string")
All messages that contain string in their body.
(text "string")
All messages that contain string in their header or body.
(larger size)
All messages that are larger than size (in bytes).
(smaller size)
All messages that are smaller than size (in bytes).
(before date)
All messages that were received before date, which must be in the
form `d[d]-mon-yyyy', where `d' denotes the day of the month as one
or two digits, `mon' is the name of the month - one of `Jan Feb Mar
Apr May Jun Jul Aug Sep Oct Nov Dec', and `yyyy' is the year as
four digits, for example `28-Dec-2012'.
(on date)
All messages that were received on the specified date.
(since date)
All messages that were received since the specified date.
(sentbefore date)
All messages that were sent on the specified date.
(senton date)
All messages that were sent on the specified date.
(sentsince date)
All messages that were sent since the specified date.
() The same criterion as for the previous search. This specification
cannot be used as part of another criterion. If the previous com-
mand line contained more than one independent criterion then the
last of those criteria is used.
On terminal control and line editor
[Option] Terminal control through one of the standard UNIX libraries,
Termcap Access Library (libtermcap, -ltermcap) or Terminal Information
Library (libterminfo, -lterminfo), may be available. For the TERMinal
defined in the environment interactive usage aspects, for example
Coloured display, and insight of cursor and function keys for the Mailx-
Line-Editor (MLE), will be enhanced or enabled. Library interaction can
be disabled on a per-invocation basis via termcap-disable, whereas the
internal variable termcap is always used as a preferred source of termi-
nal capabilities. (For a usage example see the FAQ entry Not
"defunctional", but the editor key does not work.)
[Option] The built-in Mailx-Line-Editor (MLE) should work in all environ-
ments which comply to the ISO C standard ISO/IEC 9899/AMD1:1995
(``ISO C90, Amendment 1''), and will support wide glyphs if possible (the
necessary functionality had been removed from ISO C, but was included in
X/Open Portability Guide Issue 4 (``XPG4'')). Usage of a line editor in
interactive mode can be prevented by setting line-editor-disable. Espe-
cially if the [Option]al terminal control support is missing setting
entries in termcap will help shall the MLE misbehave, see there for more.
The MLE can support a little bit of colour.
[Option] If the history feature is available then input from line editor
prompts will be saved in a history list that can be searched in and be
expanded from. Such saving can be prevented by prefixing input with any
amount of whitespace. Aspects of history, like allowed content and maxi-
mum size, as well as whether history shall be saved persistently, can be
configured with the internal variables history-file, history-gabby,
history-gabby-persist and history-size. There also exists the macro hook
on-history-addition which can be used to apply finer control on what
enters history.
The MLE supports a set of editing and control commands. By default (as)
many (as possible) of these will be assigned to a set of single-letter
control codes, which should work on any terminal (and can be generated by
holding the ``control'' key while pressing the key of desire, for example
`control-D'). If the [Option]al bind command is available then the MLE
commands can also be accessed freely by assigning the command name, which
is shown in parenthesis in the list below, to any desired key-sequence,
and the MLE will instead and also use bind to establish its built-in key
bindings (more of them if the [Option]al terminal control is available),
an action which can then be suppressed completely by setting
line-editor-no-defaults. Shell-style argument quoting notation is used
in the following:
`\cA' Go to the start of the line (mle-go-home).
`\cB' Move the cursor backward one character (mle-go-bwd).
`\cC' raise(3) `SIGINT' (mle-raise-int).
`\cD' Forward delete the character under the cursor; quits S-nail if
used on the empty line unless the internal variable ignoreeof is
set (mle-del-fwd).
`\cE' Go to the end of the line (mle-go-end).
`\cF' Move the cursor forward one character (mle-go-fwd).
`\cG' Cancel current operation, full reset. If there is an active his-
tory search or tabulator expansion then this command will first
reset that, reverting to the former line content; thus a second
reset is needed for a full reset in this case (mle-reset).
`\cH' Backspace: backward delete one character (mle-del-bwd).
`\cI' [Only new quoting rules] Horizontal tabulator: try to expand the
word before the cursor, supporting the usual Filename
transformations (mle-complete; this is affected by
mle-quote-rndtrip and line-editor-cpl-word-breaks).
`\cJ' Newline: commit the current line (mle-commit).
`\cK' Cut all characters from the cursor to the end of the line
(mle-snarf-end).
`\cL' Repaint the line (mle-repaint).
`\cN' [Option] Go to the next history entry (mle-hist-fwd).
`\cO' ([Option]ally context-dependent) Invokes the command dt.
`\cP' [Option] Go to the previous history entry (mle-hist-bwd).
`\cQ' Toggle roundtrip mode shell quotes, where produced, on and off
(mle-quote-rndtrip). This setting is temporary, and will be for-
gotten once the command line is committed; also see shcodec.
`\cR' [Option] Complete the current line from (the remaining) older his-
tory entries (mle-hist-srch-bwd).
`\cS' [Option] Complete the current line from (the remaining) newer his-
tory entries (mle-hist-srch-fwd).
`\cT' Paste the snarf buffer (mle-paste).
`\cU' The same as `\cA' followed by `\cK' (mle-snarf-line).
`\cV' Prompts for a Unicode character (hexadecimal number without pre-
fix, see vexpr) to be inserted (mle-prompt-char). Note this com-
mand needs to be assigned to a single-letter control code in order
to become recognized and executed during input of a key-sequence
(only three single-letter control codes can be used for that
shortcut purpose); this control code is then special-treated and
thus cannot be part of any other sequence (because it will trigger
the mle-prompt-char function immediately).
`\cW' Cut the characters from the one preceding the cursor to the pre-
ceding word boundary (mle-snarf-word-bwd).
`\cX' Move the cursor forward one word boundary (mle-go-word-fwd).
`\cY' Move the cursor backward one word boundary (mle-go-word-bwd).
`\cZ' raise(3) `SIGTSTP' (mle-raise-tstp).
`\c[' Escape: reset a possibly used multibyte character input state
machine and [Option]ally a lingering, incomplete key binding
(mle-cancel). This command needs to be assigned to a single-let-
ter control code in order to become recognized and executed during
input of a key-sequence (only three single-letter control codes
can be used for that shortcut purpose). This control code may
also be part of a multi-byte sequence, but if a sequence is active
and the very control code is currently also an expected input,
then the active sequence takes precedence and will consume the
control code.
`\c\' ([Option]ally context-dependent) Invokes the command `z+'.
`\c]' ([Option]ally context-dependent) Invokes the command `z$'.
`\c^' ([Option]ally context-dependent) Invokes the command `z0'.
`\c_' Cut the characters from the one after the cursor to the succeeding
word boundary (mle-snarf-word-fwd).
`\c?' Backspace: mle-del-bwd.
- mle-bell: ring the audible bell.
- [Option] mle-clear-screen: move the cursor home and clear the
screen.
- mle-fullreset: different to mle-reset this will immediately reset
a possibly active search etc.
- mle-go-screen-bwd: move the cursor backward one screen width.
- mle-go-screen-fwd: move the cursor forward one screen width.
- mle-raise-quit: raise(3) `SIGQUIT'.
Coloured display
[Option] Colours and font attributes through ANSI a.k.a. ISO 6429 SGR
(select graphic rendition) escape sequences are optionally supported.
Usage of colours and font attributes solely depends upon the capability
of the detected terminal type (TERM), and as fine-tuned through termcap.
Colours and font attributes can be managed with the multiplexer command
colour, and uncolour removes the given mappings. Setting colour-disable
suppresses usage of colour and font attribute sequences, while leaving
established mappings unchanged.
Whether actually applicable colour and font attribute sequences should
also be generated when output is going to be paged through the external
PAGER (also see crt) depends upon the setting of colour-pager, because
pagers usually need to be configured in order to support ISO escape
sequences. Knowledge of some widely used pagers is however built-in, and
in a clean environment it is often enough to simply set colour-pager;
please refer to that variable for more on this topic.
It might make sense to conditionalize colour setup on interactive mode
via if (`terminal' indeed means ``interactive''):
if terminal && "$features" =% ,+colour,
colour iso view-msginfo ft=bold,fg=green
colour iso view-header ft=bold,fg=red (from|subject) # regex
colour iso view-header fg=red
uncolour iso view-header from,subject
colour iso view-header ft=bold,fg=magenta,bg=cyan
colour 256 view-header ft=bold,fg=208,bg=230 "subject,from"
colour mono view-header ft=bold
colour mono view-header ft=bold,ft=reverse subject,from
endif
Handling spam
[Option] S-nail can make use of several spam interfaces for the purpose
of identification of, and, in general, dealing with spam messages. A
precondition of most commands in order to function is that the
spam-interface variable is set to one of the supported interfaces.
Specifying messages that have been identified as spam is possible via
their (volatile) `is-spam' state by using the `:s' and `:S' specifica-
tions, and their attrlist entries will be used when displaying the
headline in the summary of headers.
o spamrate rates the given messages and sets their `is-spam' flag
accordingly. If the spam interface offers spam scores these can be
shown in headline by using the format `%$'.
o spamham, spamspam and spamforget will interact with the Bayesian fil-
ter of the chosen interface and learn the given messages as ``ham''
or ``spam'', respectively; the last command can be used to cause
``unlearning'' of messages; it adheres to their current `is-spam'
state and thus reverts previous teachings.
o spamclear and spamset will simply set and clear, respectively, the
mentioned volatile `is-spam' message flag, without any interface
interaction.
The spamassassin(1) based spam-interface `spamc' requires a running
instance of the spamd(1) server in order to function, started with the
option --allow-tell shall Bayesian filter learning be possible.
$ spamd -i localhost:2142 -i /tmp/.spamsock -d [-L] [-l]
$ spamd --listen=localhost:2142 --listen=/tmp/.spamsock \
--daemonize [--local] [--allow-tell]
Thereafter S-nail can make use of these interfaces:
$ s-nail -Sspam-interface=spamc -Sspam-maxsize=500000 \
-Sspamc-command=/usr/local/bin/spamc \
-Sspamc-arguments="-U /tmp/.spamsock" -Sspamc-user=
or
$ s-nail -Sspam-interface=spamc -Sspam-maxsize=500000 \
-Sspamc-command=/usr/local/bin/spamc \
-Sspamc-arguments="-d localhost -p 2142" -Sspamc-user=
Using the generic filter approach allows usage of programs like
bogofilter(1). Here is an example, requiring it to be accessible via
PATH:
$ s-nail -Sspam-interface=filter -Sspam-maxsize=500000 \
-Sspamfilter-ham="bogofilter -n" \
-Sspamfilter-noham="bogofilter -N" \
-Sspamfilter-nospam="bogofilter -S" \
-Sspamfilter-rate="bogofilter -TTu 2>/dev/null" \
-Sspamfilter-spam="bogofilter -s" \
-Sspamfilter-rate-scanscore="1;^(.+)$"
Because messages must exist on local storage in order to be scored (or
used for Bayesian filter training), it is possibly a good idea to perform
the local spam check last. Spam can be checked automatically when open-
ing specific folders by setting a specialized form of the internal vari-
able folder-hook.
define spamdelhook {
# Server side DCC
spamset (header x-dcc-brand-metrics "bulk")
# Server-side spamassassin(1)
spamset (header x-spam-flag "YES")
del :s # TODO we HAVE to be able to do `spamrate :u ! :sS'
move :S +maybe-spam
spamrate :u
del :s
move :S +maybe-spam
}
set folder-hook-SOMEFOLDER=spamdelhook
See also the documentation for the variables spam-interface,
spam-maxsize, spamc-command, spamc-arguments, spamc-user, spamfilter-ham,
spamfilter-noham, spamfilter-nospam, spamfilter-rate and
spamfilter-rate-scanscore.
COMMANDS
S-nail reads input in lines. An unquoted reverse solidus `\' at the end
of a command line ``escapes'' the newline character: it is discarded and
the next line of input is used as a follow-up line, with all leading
whitespace removed; once an entire line is completed, the whitespace
characters space, tabulator, newline as well as those defined by the
variable ifs are removed from the beginning and end. Placing any white-
space characters at the beginning of a line will prevent a possible addi-
tion of the command line to the [Option]al history.
The beginning of such input lines is then scanned for the name of a known
command: command names may be abbreviated, in which case the first com-
mand that matches the given prefix will be used. Command modifiers may
prefix a command in order to modify its behaviour. A name may also be a
commandalias, which will become expanded until no more expansion is pos-
sible. Once the command that shall be executed is known, the remains of
the input line will be interpreted according to command-specific rules,
documented in the following.
This behaviour is different to the sh(1)ell, which is a programming lan-
guage with syntactic elements of clearly defined semantics, and therefore
capable to sequentially expand and evaluate individual elements of a
line. `? set one=value two=$one' for example will never possibly assign
value to one, because the variable assignment is performed no sooner but
by the command (set), long after the expansion happened.
A list of all commands in lookup order is dumped by the command list.
[Option]ally the command help (or ?), when given an argument, will show a
documentation string for the command matching the expanded argument, as
in `?t', which should be a shorthand of `?type'; with these documentation
strings both commands support a more verbose listing mode which includes
the argument type of the command and other information which applies; a
handy suggestion might thus be:
? define __xv {
# Before v15: need to enable sh(1)ell-style on _entire_ line!
localopts yes;wysh set verbose;ignerr eval "${@}";return ${?}
}
? commandalias xv '\call __xv'
? xv help set
Command modifiers
Commands may be prefixed by none to multiple command modifiers. Some
command modifiers can be used with a restricted set of commands only, the
verbose version of list will ([Option]ally) show which modifiers apply.
o The modifier reverse solidus \, to be placed first, prevents
commandalias expansions on the remains of the line, for example
`\echo' will always evaluate the command echo, even if an (com-
mand)alias of the same name exists. commandalias content may itself
contain further command modifiers, including an initial reverse
solidus to prevent further expansions.
o The modifier ignerr indicates that any error generated by the follow-
ing command should be ignored by the state machine and not cause a
program exit with enabled errexit or for the standardized exit cases
in posix mode. ?, one of the INTERNAL VARIABLES, will be set to the
real exit status of the command regardless.
o local will alter the called command to apply changes only temporar-
ily, local to block-scope, and can thus only be used inside of a
defined macro or an account definition. Specifying it implies the
modifier wysh. Local variables will not be inherited by macros
deeper in the call chain, and all local settings will be garbage col-
lected once the local scope is left. To record and unroll changes in
the global scope use the command localopts.
o scope does yet not implement any functionality.
o u does yet not implement any functionality.
o Some commands support the vput modifier: if used, they expect the
name of a variable, which can itself be a variable, i.e., shell
expansion is applied, as their first argument, and will place their
computation result in it instead of the default location (it is usu-
ally written to standard output).
The given name will be tested for being a valid sh(1) variable name,
and may therefore only consist of upper- and lowercase characters,
digits, and the underscore; the hyphen-minus may be used as a non-
portable extension; digits may not be used as first, hyphen-minus may
not be used as last characters. In addition the name may either not
be one of the known INTERNAL VARIABLES, or must otherwise refer to a
writable (non-boolean) value variable. The actual put operation may
fail nonetheless, for example if the variable expects a number argu-
ment only a number will be accepted. Any error during these opera-
tions causes the command as such to fail, and the error number ! will
be set to ^ERR-NOTSUP, the exit status ? should be set to `-1', but
some commands deviate from the latter, which is documented.
o Last, but not least, the modifier wysh can be used for some old and
established commands to choose the new Shell-style argument quoting
rules over the traditional Old-style argument quoting. This modifier
is implied if v15-compat is set to a non-empty value.
Old-style argument quoting
[v15 behaviour may differ] This section documents the traditional and
POSIX standardized style of quoting non-message list arguments to com-
mands which expect this type of arguments: whereas still used by the
majority of such commands, the new Shell-style argument quoting may be
available even for those via wysh, one of the Command modifiers. None-
theless care must be taken, because only new commands have been designed
with all the capabilities of the new quoting rules in mind, which can,
for example generate control characters.
o An argument can be enclosed between paired double-quotes
`"argument"' or single-quotes `'argument''; any whitespace,
shell word expansion, or reverse solidus characters (except as
described next) within the quotes are treated literally as part
of the argument. A double-quote will be treated literally
within single-quotes and vice versa. Inside such a quoted
string the actually used quote character can be used nonethe-
less by escaping it with a reverse solidus `\', as in
`"y\"ou"'.
o An argument that is not enclosed in quotes, as above, can usu-
ally still contain space characters if those spaces are reverse
solidus escaped, as in `you\ are'.
o A reverse solidus outside of the enclosing quotes is discarded
and the following character is treated literally as part of the
argument.
Shell-style argument quoting
sh(1)ell-style, and therefore POSIX standardized, argument parsing and
quoting rules are used by most commands. [v15 behaviour may differ] Most
new commands only support these new rules and are flagged [Only new quot-
ing rules], some elder ones can use them with the command modifier wysh;
in the future only this type of argument quoting will remain.
A command line is parsed from left to right and an input token is com-
pleted whenever an unquoted, otherwise ignored, metacharacter is seen.
Metacharacters are vertical bar |, ampersand &, semicolon ;, as well as
all characters from the variable ifs, and / or space, tabulator, newline.
The additional metacharacters left and right parenthesis (, ) and less-
than and greater-than signs <, > that the sh(1) supports are not used,
and are treated as ordinary characters: for one these characters are a
vivid part of email addresses, and it seems highly unlikely that their
function will become meaningful to S-nail.
Compatibility note: [v15 behaviour may differ] Please note that
even many new-style commands do not yet honour ifs to parse their
arguments: whereas the sh(1)ell is a language with syntactic ele-
ments of clearly defined semantics, S-nail parses entire input
lines and decides on a per-command base what to do with the rest of
the line. This also means that whenever an unknown command is seen
all that S-nail can do is cancellation of the processing of the
remains of the line.
It also often depends on an actual subcommand of a multiplexer com-
mand how the rest of the line should be treated, and until v15 we
are not capable to perform this deep inspection of arguments.
Nonetheless, at least the following commands which work with posi-
tional parameters fully support ifs for an almost shell-compatible
field splitting: call, call_if, read, vpospar, xcall.
Any unquoted number sign `#' at the beginning of a new token starts a
comment that extends to the end of the line, and therefore ends argument
processing. An unquoted dollar sign `$' will cause variable expansion of
the given name, which must be a valid sh(1)ell-style variable name (see
vput): INTERNAL VARIABLES as well as ENVIRONMENT (shell) variables can be
accessed through this mechanism, brace enclosing the name is supported
(i.e., to subdivide a token).
Whereas the metacharacters space, tabulator, newline only complete an
input token, vertical bar |, ampersand & and semicolon ; also act as con-
trol operators and perform control functions. For now supported is semi-
colon ;, which terminates a single command, therefore sequencing the com-
mand line and making the remainder of the line a subject to reevaluation.
With sequencing, multiple command argument types and quoting rules may
therefore apply to a single line, which can become problematic before
v15: e.g., the first of the following will cause surprising results.
? echo one; set verbose; echo verbose=$verbose.
? echo one; wysh set verbose; echo verbose=$verbose.
Quoting is a mechanism that will remove the special meaning of metachar-
acters and reserved words, and will prevent expansion. There are four
quoting mechanisms: the escape character, single-quotes, double-quotes
and dollar-single-quotes:
o The literal value of any character can be preserved by preced-
ing it with the escape character reverse solidus `\'.
o Arguments which are enclosed in `'single-quotes'' retain their
literal value. A single-quote cannot occur within single-
quotes.
o The literal value of all characters enclosed in `"double-
quotes"' is retained, with the exception of dollar sign `$',
which will cause variable expansion, as above, backquote (grave
accent) ``', (which not yet means anything special), reverse
solidus `\', which will escape any of the characters dollar
sign `$' (to prevent variable expansion), backquote (grave
accent) ``', double-quote `"' (to prevent ending the quote) and
reverse solidus `\' (to prevent escaping, i.e., to embed a
reverse solidus character as-is), but has no special meaning
otherwise.
o Arguments enclosed in `$'dollar-single-quotes'' extend normal
single quotes in that reverse solidus escape sequences are
expanded as follows:
`\a' bell control character (ASCII and ISO-10646 BEL).
`\b' backspace control character (ASCII and ISO-10646 BS).
`\E' escape control character (ASCII and ISO-10646 ESC).
`\e' the same.
`\f' form feed control character (ASCII and ISO-10646 FF).
`\n' line feed control character (ASCII and ISO-10646 LF).
`\r' carriage return control character (ASCII and ISO-10646
CR).
`\t' horizontal tabulator control character (ASCII and
ISO-10646 HT).
`\v' vertical tabulator control character (ASCII and
ISO-10646 VT).
`\\' emits a reverse solidus character.
`\'' single quote.
`\"' double quote (escaping is optional).
`\NNN' eight-bit byte with the octal value `NNN' (one to three
octal digits), optionally prefixed by an additional
`0'. A 0 byte will suppress further output for the
quoted argument.
`\xHH' eight-bit byte with the hexadecimal value `HH' (one or
two hexadecimal characters, no prefix, see vexpr). A 0
byte will suppress further output for the quoted argu-
ment.
`\UHHHHHHHH'
the Unicode / ISO-10646 character with the hexadecimal
codepoint value `HHHHHHHH' (one to eight hexadecimal
characters) -- note that Unicode defines the maximum
codepoint ever to be supported as `0x10FFFF' (in planes
of `0xFFFF' characters each). This escape is only sup-
ported in locales that support Unicode (see Character
sets), in other cases the sequence will remain unex-
panded unless the given code point is ASCII compatible
or (if the [Option]al character set conversion is
available) can be represented in the current locale.
The character NUL will suppress further output for the
quoted argument.
`\uHHHH'
Identical to `\UHHHHHHHH' except it takes only one to
four hexadecimal characters.
`\cX' Emits the non-printable (ASCII and compatible) C0 con-
trol codes 0 (NUL) to 31 (US), and 127 (DEL). Print-
able representations of ASCII control codes can be cre-
ated by mapping them to a different, visible part of
the ASCII character set. Adding the number 64 achieves
this for the codes 0 to 31, here 7 (BEL): `7 + 64 = 71
= G'. The real operation is a bitwise logical XOR with
64 (bit 7 set, see vexpr), thus also covering code 127
(DEL), which is mapped to 63 (question mark):
`? vexpr ^ 127 64'.
Whereas historically circumflex notation has often been
used for visualization purposes of control codes, as in
`^G', the reverse solidus notation has been standard-
ized: `\cG'. Some control codes also have standardized
(ISO-10646, ISO C) aliases, as shown above (`\a', `\n',
`\t' etc) : whenever such an alias exists it will be
used for display purposes. The control code NUL
(`\c@', a non-standard extension) will suppress further
output for the remains of the token (which may extend
beyond the current quote), or, depending on the con-
text, the remains of all arguments for the current com-
mand.
`\$NAME'
Non-standard extension: expand the given variable name,
as above. Brace enclosing the name is supported.
`\`{command}'
Not yet supported, just to raise awareness: Non-stan-
dard extension.
Caveats:
? echo 'Quotes '${HOME}' and 'tokens" differ!"# no comment
? echo Quotes ${HOME} and tokens differ! # comment
? echo Don"'"t you worry$'\x21' The sun shines on us. $'\u263A'
Message list arguments
Many commands operate on message list specifications, as documented in
Specifying messages. The argument input is first split into individual
tokens via Shell-style argument quoting, which are then interpreted as
the mentioned specifications. If no explicit message list has been spec-
ified, many commands will search for and use the next message forward
that satisfies the commands' requirements, and if there are no messages
forward of the current message, the search proceeds backwards; if there
are no good messages at all to be found, an error message is shown and
the command is aborted. The verbose output of the command list will
indicate whether a command searches for a default message, or not.
Raw data arguments for codec commands
A special set of commands, which all have the string ``codec'' in their
name, like addrcodec, shcodec, urlcodec, take raw string data as input,
which means that the content of the command input line is passed com-
pletely unexpanded and otherwise unchanged: like this the effect of the
actual codec is visible without any noise of possible shell quoting rules
etc., i.e., the user can input one-to-one the desired or questionable
data. To gain a level of expansion, the entire command line can be
evaluated first, for example
? vput shcodec res encode /usr/Schones Wetter/heute.txt
? echo $res
$'/usr/Sch\u00F6nes Wetter/heute.txt'
? shcodec d $res
$'/usr/Sch\u00F6nes Wetter/heute.txt'
? eval shcodec d $res
/usr/Schones Wetter/heute.txt
Filename transformations
Filenames, where expected, and unless documented otherwise, are subse-
quently subject to the following filename transformations, in sequence:
o If the given name is a registered shortcut, it will be replaced
with the expanded shortcut. This step is mostly taken for
folders only.
o The filename is matched against the following patterns or
strings. But for plus +file folder expansion this step is
mostly taken for folders only.
# (Number sign) is expanded to the previous file.
% (Percent sign) is replaced by the invoking user's pri-
mary system mailbox, which either is the (itself expand-
able) inbox if that is set, the standardized absolute
pathname indicated by MAIL if that is set, or a built-in
compile-time default otherwise. When opening a folder
the used name is actively checked for being a primary
mailbox, first against inbox, then against MAIL.
%user Expands to the primary system mailbox of user (and never
the value of inbox, regardless of its actual setting).
& (Ampersand) is replaced with the invoking user's sec-
ondary mailbox, the MBOX.
+file Refers to a file in the folder directory (if that vari-
able is set).
%:filespec Expands to the same value as filespec, but has spe-
cial meaning when used with, for example, the command
folder: the file will be treated as a primary system
mailbox by, among others, the mbox and save commands,
meaning that messages that have been read in the current
session will be moved to the MBOX mailbox instead of
simply being flagged as read.
o Meta expansions may be applied to the resulting filename, as
allowed by the operation and applicable to the resulting access
protocol (also see On URL syntax and credential lookup). For
the file-protocol, a leading tilde `~' character will be
replaced by the expansion of HOME, except when followed by a
valid user name, in which case the home directory of the given
user is used instead.
A shell expansion as if specified in double-quotes (see
Shell-style argument quoting) may be applied, so that any
occurrence of `$VARIABLE' (or `${VARIABLE}') will be replaced
by the expansion of the variable, if possible; INTERNAL
VARIABLES as well as ENVIRONMENT (shell) variables can be
accessed through this mechanism.
Shell pathname wildcard pattern expansions (glob(7)) may be
applied as documented. If the fully expanded filename results
in multiple pathnames and the command is expecting only one
file, an error results.
In interactive context, in order to allow simple value accep-
tance (via ``ENTER''), arguments will usually be displayed in a
properly quoted form, so a file `diet\ is \curd.txt' may be
displayed as `'diet\ is \curd.txt''.
Commands
The following commands are available:
! Executes the SHELL command which follows, replacing unescaped
exclamation marks with the previously executed command if the
internal variable bang is set. This command supports vput as docu-
mented in Command modifiers, and manages the error number !. A 0
or positive exit status ? reflects the exit status of the command,
negative ones that an error happened before the command was exe-
cuted, or that the program did not exit cleanly, but maybe due to a
signal: the error number is ^ERR-CHILD, then.
In conjunction with the vput modifier the following special cases
exist: a negative exit status occurs if the collected data could
not be stored in the given variable, which is a ^ERR-NOTSUP error
that should otherwise not occur. ^ERR-CANCELED indicates that no
temporary file could be created to collect the command output at
first glance. In case of catchable out-of-memory situations
^ERR-NOMEM will occur and S-nail will try to store the empty
string, just like with all other detected error conditions.
# The comment-command causes the entire line to be ignored. Note:
this really is a normal command which' purpose is to discard its
arguments, not a ``comment-start'' indicating special character,
which means that for example trailing comments on a line are not
possible (except for commands which use Shell-style argument
quoting).
+ Goes to the next message in sequence and types it (like ``ENTER'').
- Display the preceding message, or the n'th previous message if
given a numeric argument n.
= Shows the message number of the current message (the ``dot'') when
used without arguments, that of the given list otherwise. Output
numbers will be separated from each other with the first character
of ifs, and followed by the first character of if-ws, if that is
not empty and not identical to the first. If that results in no
separation at all a space character is used. This command supports
vput (see Command modifiers), and manages the error number !.
? [Option] Show a brief summary of commands. [Option] Given an argu-
ment a synopsis for the command in question is shown instead; com-
mands can be abbreviated in general and this command can be used to
see the full expansion of an abbreviation including the synopsis,
try, for example `?h', `?hel' and `?help' and see how the output
changes. To avoid that aliases are resolved the modifier \ can be
prepended to the argument, but note it must be quoted. This mode
also supports a more verbose output, which will provide the infor-
mation documented for list.
| A synonym for the pipe command.
account, unaccount
(ac, una) Creates, selects or lists (an) account(s). Accounts are
special incarnations of defined macros and group commands and vari-
able settings which together usually arrange the environment for
the purpose of creating an email account. Different to normal
macros settings which are covered by localopts - here by default
enabled! - will not be reverted before the account is changed
again. The special account `null' (case-insensitive) always
exists, and all but it can be deleted by the latter command, and in
one operation with the special name `*'. Also for all but it a
possibly set on-account-cleanup hook is called once they are left,
also for program exit.
Without arguments a listing of all defined accounts is shown. With
one argument the given account is activated: the system inbox of
that account will be activated (as via folder), a possibly
installed folder-hook will be run, and the internal variable
account will be updated. The two argument form behaves identical
to defining a macro as via define. Important settings for accounts
include folder, from, hostname, inbox, mta, password and user (On
URL syntax and credential lookup), as well as things like
tls-config-pairs (Encrypted network communication), and protocol
specifics like imap-auth, pop3-auth, smtp-auth.
account myisp {
set folder=~/mail inbox=+syste.mbox record=+sent.mbox
set from='(My Name) myname AT myisp.example'
set mta=smtp://mylogin AT smtp.example
}
addrcodec
Perform email address codec transformations on raw-data argument,
rather according to email standards (RFC 5322; [v15 behaviour may
differ] will furtherly improve). Supports vput (see Command
modifiers), and manages the error number !. The first argument
must be either [+[+[+]]]e[ncode], d[ecode], s[kin] or skinl[ist]
and specifies the operation to perform on the rest of the line.
Decoding will show how a standard-compliant MUA will display the
given argument, which should be an email address. Please be aware
that most MUAs have difficulties with the address standards, and
vary wildly when (comments) in parenthesis, ``double-quoted''
strings, or quoted-pairs, as below, become involved. [v15 behav-
iour may differ] S-nail currently does not perform decoding when
displaying addresses.
Skinning is identical to decoding but only outputs the plain
address, without any string, comment etc. components. Another dif-
ference is that it may fail with the error number ! set to
^ERR-INVAL if decoding fails to find a(n) (valid) email address, in
which case the unmodified input will be output again.
skinlist first performs a skin operation, and thereafter checks a
valid address for whether it is a registered mailing list (see
mlist and mlsubscribe), eventually reporting that state in the
error number ! as ^ERR-EXIST. (This state could later become over-
written by an I/O error, though.)
Encoding supports four different modes, lesser automated versions
can be chosen by prefixing one, two or three plus signs: the stan-
dard imposes a special meaning on some characters, which thus have
to be transformed to so-called quoted-pairs by pairing them with a
reverse solidus `\' in order to remove the special meaning; this
might change interpretation of the entire argument from what has
been desired, however! Specify one plus sign to remark that paren-
thesis shall be left alone, two for not turning double quotation
marks into quoted-pairs, and three for also leaving any user-speci-
fied reverse solidus alone. The result will always be valid, if a
successful exit status is reported ([v15 behaviour may differ] the
current parser fails this assertion for some constructs). [v15 be-
haviour may differ] Addresses need to be specified in between angle
brackets `<', `>' if the construct becomes more difficult, other-
wise the current parser will fail; it is not smart enough to guess
right.
? addrc enc "Hey, you",<diet AT exam.ple>\ out\ there
"\"Hey, you\", \\ out\\ there" <diet AT exam.ple>
? addrc d "\"Hey, you\", \\ out\\ there" <diet AT exam.ple>
"Hey, you", \ out\ there <diet AT exam.ple>
? addrc s "\"Hey, you\", \\ out\\ there" <diet AT exam.ple>
diet AT exam.ple
alias, unalias
[Only new quoting rules](a, una) Define or list, and remove,
respectively, address aliases, which are a method of creating per-
sonal distribution lists that map a single name to none to multiple
receivers, to be expanded after Compose mode is left; the expansion
correlates with metoo. The latter command removes all given
aliases, the special name asterisk `*' will remove all existing
aliases. When used without arguments the former shows a list of
all currently known aliases, with one argument only the target(s)
of the given one. When given two arguments, hyphen-minus `-' being
the first, the target(s) of the second is/are expanded recursively.
In all other cases the given alias is newly defined, or will be
appended to: arguments must either be themselves valid alias names,
or any other address type (see On sending mail, and non-interactive
mode). Recursive expansion of aliases can be prevented by prefix-
ing the desired argument with the modifier reverse solidus \. A
valid alias name conforms to mta-aliases syntax, but follow-up
characters can also be the number sign `#', colon `:', commercial
at `@,' exclamation mark `!', period `.' as well as ``any character
that has the high bit set''. The dollar sign `$' may be the last
character. The number sign `#' may need Shell-style argument
quoting.
[v15 behaviour may differ] Unfortunately the colon is currently not
supported, as it interferes with normal address parsing rules.
[v15 behaviour may differ] Such high bit characters will likely
cause warnings at the moment for the same reasons why colon is
unsupported; also, in the future locale dependent character set
validity checks will be performed.
? alias cohorts bill jkf mark kridle@ucbcory ~/cohorts.mbox
? alias mark mark AT exam.ple
? set mta-aliases=/etc/aliases
alternates, unalternates
[Only new quoting rules] (alt) Manage a list of alternate addresses
or names of the active user, members of which will be removed from
recipient lists (except one). There is a set of implicit alter-
nates which is formed of the values of LOGNAME, from, sender and
reply-to. from will not be used if sender is set. The latter com-
mand removes the given list of alternates, the special name `*'
will discard all existing alternate names.
The former command manages the error number !. It shows the cur-
rent set of alternates when used without arguments; in this mode
only it also supports vput (see Command modifiers). Otherwise the
given arguments (after being checked for validity) are appended to
the list of alternate names; in posix mode they replace that list
instead.
answered, unanswered
Take a message lists and mark each message as (not) having been
answered. Messages will be marked answered when being replyd to
automatically if the markanswered variable is set. See the section
Message states.
bind, unbind
[Option][Only new quoting rules] The bind command extends the MLE
(see On terminal control and line editor) with freely configurable
key bindings. The latter command removes from the given context
the given key binding, both of which may be specified as a wildcard
`*', so that `unbind * *' will remove all bindings of all contexts.
Due to initialization order unbinding will not work for built-in
key bindings upon program startup, however: please use
line-editor-no-defaults for this purpose instead.
With zero arguments, or with a context name the former command
shows all key bindings (of the given context; an asterisk `*' will
iterate over all contexts); a more verbose listing will be produced
if either of debug or verbose are set. With two or more arguments
a specific binding is shown, or (re)established: the first argument
is the context to which the binding shall apply, the second argu-
ment is a comma-separated list of the ``keys'' which form the bind-
ing. Further arguments will be joined to form the expansion, and
cause the binding to be created or updated. To indicate that a
binding shall not be auto-committed, but that the expansion shall
instead be furtherly editable by the user, a commercial at `@'
(that will be removed) can be placed last in the expansion, from
which leading and trailing whitespace will finally be removed.
Reverse solidus cannot be used as the last character of expansion.
An empty expansion will be rejected.
Contexts define when a binding applies, i.e., a binding will not be
seen unless the context for which it is defined for is currently
active. This is not true for the shared binding `base', which is
the foundation for all other bindings and as such always applies,
its bindings, however, only apply secondarily. The available con-
texts are the shared `base', the `default' context which is used in
all not otherwise documented situations, and `compose', which
applies only to Compose mode.
Bindings are specified as a comma-separated list of byte-sequences,
where each list entry corresponds to one ``key'' (press). Byte
sequence boundaries will be forcefully terminated after
bind-inter-byte-timeout milliseconds, whereas key sequences can be
timed out via bind-inter-key-timeout. A list entry may, indicated
by a leading colon character `:', also refer to the name of a ter-
minal capability; several dozen names are compiled in and may be
specified either by their terminfo(5), or, if existing, by their
termcap(5) name, regardless of the actually used [Option]al termi-
nal control library. But any capability may be used, as long as
the name is resolvable by the [Option]al control library, or was
defined via the internal variable termcap. Input sequences are not
case-normalized, an exact match is required to update or remove a
binding. It is advisable to use an initial escape or other control
character (like `\cA') for user (as opposed to purely terminal
capability based) bindings in order to avoid ambiguities; it also
reduces search time. Examples:
? bind base a,b echo one
? bind base $'\E',d mle-snarf-word-fwd # Esc(ape)
? bind base $'\E',$'\c?' mle-snarf-word-bwd # Esc,Delete
? bind default $'\cA',:khome,w 'echo Editable binding@'
? bind default a,b,c rm -irf / @ # Also editable
? bind default :kf1 File %
? bind compose :kf1 ~v
Note that the entire comma-separated list is first parsed (over) as
a shell-token with whitespace as the field separator, then parsed
and expanded for real with comma as the field separator, therefore
whitespace needs to be properly quoted, see Shell-style argument
quoting. Using Unicode reverse solidus escape sequences renders a
binding defunctional if the locale does not support Unicode (see
Character sets), and using terminal capabilities does so if no
(corresponding) terminal control support is (currently) available.
Adding, deleting or modifying a key binding invalidates the inter-
nal prebuilt lookup tree, it will be recreated as necessary: this
process will be visualized in most verbose as well as in debug
mode.
The following terminal capability names are built-in and can be
used in terminfo(5) or (if available) the two-letter termcap(5)
notation. See the respective manual for a list of capabilities.
The program infocmp(1) can be used to show all the capabilities of
TERM or the given terminal type; using the -x flag will also show
supported (non-standard) extensions.
kbs or kb Backspace.
kdch1 or kD Delete character.
kDC or *4 -- shifted variant.
kel or kE Clear to end of line.
kext or @9 Exit.
kich1 or kI Insert character.
kIC or #3 -- shifted variant.
khome or kh Home.
kHOM or #2 -- shifted variant.
kend or @7 End.
knp or kN Next page.
kpp or kP Previous page.
kcub1 or kl Left cursor (with more modifiers: see below).
kLFT or #4 -- shifted variant.
kcuf1 or kr Right cursor (ditto).
kRIT or %i -- shifted variant.
kcud1 or kd Down cursor (ditto).
kDN -- shifted variant (only terminfo).
kcuu1 or ku Up cursor (ditto).
kUP -- shifted variant (only terminfo).
kf0 or k0 Function key 0. Add one for each function key up
to kf9 and k9, respectively.
kf10 or k; Function key 10.
kf11 or F1 Function key 11. Add one for each function key up
to kf19 and F9, respectively.
Some terminals support key-modifier combination extensions, e.g.,
`Alt+Shift+xy'. For example, the delete key, kdch1: in its shifted
variant, the name is mutated to kDC, then a number is appended for
the states `Alt' (kDC3), `Shift+Alt' (kDC4), `Control' (kDC5),
`Shift+Control' (kDC6), `Alt+Control' (kDC7), finally
`Shift+Alt+Control' (kDC8). The same for the left cursor key,
kcub1: KLFT, KLFT3, KLFT4, KLFT5, KLFT6, KLFT7, KLFT8.
call [Only new quoting rules] Calls the given macro, which must have
been created via define (see there for more), otherwise an
^ERR-NOENT error occurs. Calling macros recursively will at some
time excess the stack size limit, causing a hard program abortion;
if recursively calling a macro is the last command of the current
macro, consider to use the command xcall, which will first release
all resources of the current macro before replacing the current
macro with the called one.
call_if
Identical to call if the given macro has been created via define,
but does not fail nor warn if the macro does not exist.
cd Synonym for chdir.
certsave
[Option] Only applicable to S/MIME signed messages. Takes an
optional message list and a filename and saves the certificates
contained within the message signatures to the named file in both
human-readable and PEM format. The certificates can later be used
to send encrypted messages to the respective message senders by
setting smime-encrypt-USER@HOST variables.
charsetalias, uncharsetalias
[Only new quoting rules] Manage alias mappings for (conversion of)
Character sets. Alias processing is not performed for INTERNAL
VARIABLES, for example charset-8bit, and mappings are ineffective
if character set conversion is not available (features does not
announce `,+iconv,'). Expansion happens recursively for cases
where aliases point to other aliases (built-in loop limit: 8).
The latter command deletes all aliases given as arguments, or all
at once when given the asterisk `*'. The former shows the list of
all currently defined aliases if used without arguments, or the
target of the given single argument; when given two arguments,
hyphen-minus `-' being the first, the second is instead expanded
recursively. In all other cases the given arguments are treated as
pairs of character sets and their desired target alias name, creat-
ing new or updating already existing aliases.
chdir
[Only new quoting rules](ch) Change the working directory to HOME
or the given argument. Synonym for cd.
collapse, uncollapse
Only applicable to `thread'ed sort mode. Takes a message list and
makes all replies to these messages invisible in header summaries,
except for `new' messages and the ``dot''. Also when a message
with collapsed replies is displayed, all of these are automatically
uncollapsed. The latter command undoes collapsing.
colour, uncolour
[Option][Only new quoting rules] Manage colour mappings of and for
a Coloured display. Without arguments the former shows all cur-
rently defined mappings. Otherwise a colour type is expected
(case-insensitively), it must be one of `256' for 256-colour termi-
nals, `8', `ansi' or `iso' for the standard 8-colour ANSI / ISO
6429 colour palette, and `1' or `mono' for monochrome terminals,
which only support (some) font attributes. Without further argu-
ments the list of all currently defined mappings of the given type
is shown (here the special `all' or `*' also show all currently
defined mappings).
Otherwise the second argument defines the mappable slot, the third
argument a (comma-separated list of) colour and font attribute
specification(s), and the optionally supported fourth argument can
be used to specify a precondition: if conditioned mappings exist
they are tested in (creation) order unless a (case-insensitive)
match has been found, and the default mapping (if any has been
established) will only be chosen as a last resort. The types of
available preconditions depend on the mappable slot, the following
of which exist:
Mappings prefixed with `mle-' are used for the [Option]al built-in
Mailx-Line-Editor (MLE, see On terminal control and line editor)
and do not support preconditions.
mle-position This mapping is used for the position indicator that
is visible when a line cannot be fully displayed on
the screen.
mle-prompt Used for the prompt.
mle-error Used for the occasionally appearing error indicator
that is joined onto prompt. [v15 behaviour may dif-
fer] Also used for error messages written on stan-
dard error .
Mappings prefixed with `sum-' are used in header summaries, and
they all understand the preconditions `dot' (the current message)
and `older' for elder messages (only honoured in conjunction with
datefield-markout-older).
sum-dotmark This mapping is used for the ``dotmark'' that can be
created with the `%>' or `%<' formats of the vari-
able headline.
sum-header For the complete header summary line except the
``dotmark'' and the thread structure.
sum-thread For the thread structure which can be created with
the `%i' format of the variable headline.
Mappings prefixed with `view-' are used when displaying messages.
view-from_ This mapping is used for so-called `From_' lines,
which are MBOX file format specific header lines
(also see mbox-rfc4155).
view-header For header lines. A comma-separated list of headers
to which the mapping applies may be given as a pre-
condition; if the [Option]al regular expression sup-
port is available then if any of the magic regular
expression characters is seen the precondition will
be evaluated as (an extended) one.
view-msginfo For the introductional message info line.
view-partinfo For MIME part info lines.
The following (case-insensitive) colour definitions and font
attributes are understood, multiple of which can be specified in a
comma-separated list:
ft= a font attribute: `bold', `reverse' or `underline'. It is
possible (and often applicable) to specify multiple font
attributes for a single mapping.
fg= foreground colour attribute, in order (numbers 0 - 7) `black',
`red', `green', `brown', `blue', `magenta', `cyan' or `white'.
To specify a 256-colour mode a decimal number colour specifi-
cation in the range 0 to 255, inclusive, is supported, and
interpreted as follows:
0 - 7 the standard ISO 6429 colours, as above.
8 - 15 high intensity variants of the standard colours.
16 - 231 216 colours in tuples of 6.
232 - 255 grayscale from black to white in 24 steps.
#!/bin/sh -
fg() { printf "\033[38;5;${1}m($1)"; }
bg() { printf "\033[48;5;${1}m($1)"; }
i=0
while [ $i -lt 256 ]; do fg $i; i=$(($i + 1)); done
printf "\033[0m\n"
i=0
while [ $i -lt 256 ]; do bg $i; i=$(($i + 1)); done
printf "\033[0m\n"
bg= background colour attribute (see fg= for possible values).
The command uncolour will remove for the given colour type (the
special type `*' selects all) the given mapping; if the optional
precondition argument is given only the exact tuple of mapping and
precondition is removed. The special name `*' will remove all map-
pings (no precondition allowed), thus `uncolour * *' will remove
all established mappings.
commandalias, uncommandalias
[Only new quoting rules] Define or list, and remove, respectively,
command aliases. An (command)alias can be used everywhere a normal
command can be used, but always takes precedence: any arguments
that are given to the command alias are joined onto the alias
expansion, and the resulting string forms the command line that is,
in effect, executed. The latter command removes all given aliases,
the special name asterisk `*' will remove all existing aliases.
When used without arguments the former shows a list of all cur-
rently known aliases, with one argument only the expansion of the
given one.
With two or more arguments a command alias is defined or updated:
the first argument is the name under which the remaining command
line should be accessible, the content of which can be just about
anything. An alias may itself expand to another alias, but to
avoid expansion loops further expansion will be prevented if an
alias refers to itself or if an expansion depth limit is reached.
Explicit expansion prevention is available via reverse solidus \,
one of the Command modifiers.
? commandalias xx
s-nail: `commandalias': no such alias: xx
? commandalias xx echo hello,
? commandalias xx
commandalias xx 'echo hello,'
? xx
hello,
? xx world
hello, world
Copy (C) Similar to copy, but copy the messages to a file named after
the local part of the sender of the first message instead of taking
a filename argument; outfolder is inspected to decide on the actual
storage location.
copy (c) Copy messages to the named file and do not mark them as being
saved; otherwise identical to save.
csop [Only new quoting rules] A multiplexer command which provides C-
style string operations on 8-bit bytes without a notion of locale
settings and character sets, effectively assuming ASCII data. For
numeric and other operations refer to vexpr. vput, one of the
Command modifiers, is supported. The error result is `-1' for
usage errors and numeric results, the empty string otherwise; miss-
ing data errors, as for unsuccessful searches, result in the !
error number being set to ^ERR-NODATA. Where the question mark `?'
modifier suffix is supported, a case-insensitive (ASCII mapping)
operation mode is supported; the keyword `case' is optional so that
`find?' and `find?case' are identical.
length Queries the length of the given argument.
hash, hash32 Calculates a hash value of the given argument. The
latter will return a 32-bit result regardless of host
environment. `?' modifier suffix is supported. These
use Chris Torek's hash algorithm, the resulting hash
value is bit mixed as shown by Bret Mulvey.
find Search for the second in the first argument. Shows the
resulting 0-based offset shall it have been found. `?'
modifier suffix is supported.
substring Creates a substring of its first argument. The optional
second argument is the 0-based starting offset, a nega-
tive one counts from the end; the optional third argument
specifies the length of the desired result, a negative
length leaves off the given number of bytes at the end of
the original string; by default the entire string is
used. This operation tries to work around faulty argu-
ments (set verbose for error logs), but reports them via
the error number ! as ^ERR-OVERFLOW.
trim Trim away whitespace characters from both ends of the
argument.
trim-front Trim away whitespace characters from the begin of the
argument.
trim-end Trim away whitespace characters from the end of the argu-
ment.
cwd Show the name of the current working directory, as reported by
getcwd(3). Supports vput (see Command modifiers). The return sta-
tus is tracked via ?.
Decrypt
[Option] For unencrypted messages this command is identical to
Copy; Encrypted messages are first decrypted, if possible, and then
copied.
decrypt
[Option] For unencrypted messages this command is identical to
copy; Encrypted messages are first decrypted, if possible, and then
copied.
define, undefine
The latter command deletes the given macro, the special name `*'
will discard all existing macros. Deletion of (a) macro(s) can be
performed from within running (a) macro(s), including self-dele-
tion. Without arguments the former command prints the current list
of macros, including their content, otherwise it defines a macro,
replacing an existing one of the same name as applicable.
A defined macro can be invoked explicitly by using the call,
call_if and xcall commands, or implicitly if a macro hook is trig-
gered, for example a folder-hook. Execution of a macro body can be
stopped from within by calling return.
Temporary macro block-scope variables can be created or deleted
with the local command modifier in conjunction with the commands
set and unset, respectively. To enforce unrolling of changes made
to (global) INTERNAL VARIABLES the command localopts can be used
instead; its covered scope depends on how (i.e., ``as what'': nor-
mal macro, folder hook, hook, account switch) the macro is invoked.
Inside a called macro, the given positional parameters are implic-
itly local to the macro's scope, and may be accessed via the vari-
ables *, @, # and 1 and any other positive unsigned decimal number
less than or equal to #. Positional parameters can be shifted, or
become completely replaced, removed etc. via vpospar. A helpful
command for numeric computation and string evaluations is vexpr,
csop offers C-style byte string operations.
define name {
command1
command2
...
commandN
}
define exmac {
echo Parameter 1 of ${#} is ${1}, all: ${*} / ${@}
return 1000 0
}
call exmac Hello macro exmac!
echo ${?}/${!}/${^ERRNAME}
delete, undelete
(d, u) Marks the given message list as being or not being
`deleted', respectively; if no argument has been specified then the
usual search for a visible message is performed, as documented for
Message list arguments, showing only the next input prompt if the
search fails. Deleted messages will neither be saved in the
secondary mailbox MBOX nor will they be available for most other
commands. If the autoprint variable is set, the new ``dot'' or the
last message restored, respectively, is automatically typed; also
see dp, dt.
digmsg
[Only new quoting rules] Digging (information out of) messages is
possible through digmsg objects, which can be created for the given
message number; in Compose mode the hyphen-minus `-' will instead
open the message that is being composed. If a hyphen-minus is
given as the optional third argument then output will be generated
on the standard output channel instead of being subject to consump-
tion by the readall (or read and readsh) command(s). Note: output
must be consumed before normal processing can continue; for digmsg
objects this means each command output has to be read until the end
of file (EOF) state occurs.
The objects may be removed again by giving the same identifier used
for creation; this step could be omitted: objects will be automati-
cally closed when the active folder (mailbox) or the compose mode
is left, respectively. In all other use cases the second argument
is an object identifier, and the third and all following arguments
are interpreted as via ~^ (see COMMAND ESCAPES):
? vput = msgno; digmsg create $msgno
? digmsg $msgno header list; readall x; echon $x
210 Subject From To Message-ID References In-Reply-To
? digmsg $msgno header show Subject;readall x;echon $x
212 Subject
'Hello, world'
? digmsg remove $msgno
discard
(di) Identical to ignore. Superseded by the multiplexer
headerpick.
dp, dt
Delete the given messages and automatically type the new ``dot'' if
one exists, regardless of the setting of autoprint.
dotmove
Move the ``dot'' up or down by one message when given `+' or `-'
argument, respectively.
draft, undraft
Take message lists and mark each given message as being draft, or
not being draft, respectively, as documented in the section Message
states.
echo [Only new quoting rules](ec) Print the given strings, equivalent to
the shell utility echo(1), that is, Shell-style argument quoting
expansion is performed and, different to the otherwise identical
echon, a trailing newline is echoed. vput as documented in Command
modifiers is supported, and the error number ! is managed: if data
is stored in a variable then the return value reflects the length
of the result string in case of success and is `-1' on error.
Remarks: this command traditionally (in BSD Mail) also performed
Filename transformations, which is standard incompatible and hard
to handle because quoting transformation patterns is not possible;
the subcommand file-expand of vexpr can be used to expand file-
names.
echoerr
[Only new quoting rules] Identical to echo, but the message is
written to standard error, and prefixed by log-prefix. Also see
echoerrn. In interactive sessions the [Option]al message ring
queue for errors will be used instead, if available and vput was
not used.
echon
[Only new quoting rules] Identical to echo, but does not write or
store a trailing newline.
echoerrn
[Only new quoting rules] Identical to echoerr, but does not write
or store a trailing newline.
edit (e) Point the text EDITOR at each message from the given list in
turn. Modified contents are discarded unless the writebackedited
variable is set, and are not used unless the mailbox can be written
to and the editor returns a successful exit status. visual can be
used instead for a more display oriented editor.
elif Part of the if (see there for more), elif, else, endif conditional
-- if the condition of a preceding if was false, check the follow-
ing condition and execute the following block if it evaluates true.
else (el) Part of the if (see there for more), elif, else, endif condi-
tional -- if none of the conditions of the preceding if and elif
commands was true, the else block is executed.
endif
(en) Marks the end of an if (see there for more), elif, else, endif
conditional execution block.
environ
[Only new quoting rules] There is a strict separation in between
INTERNAL VARIABLES and the program ENVIRONMENT, which is inherited
by child processes. Some variables of the latter are however vivid
for program operation, their purpose is known, therefore they have
been integrated transparently into handling of the former, as
accessible via set and unset. To integrate any other environment
variable, and/or to export internal variables into the process
environment where they normally are not, a link needs to become
established with this command, for example
environ link PERL5LIB TZ
Afterwards changing such variables with set will cause automatic
updates of the environment, too. Sufficient system support pro-
vided (it was in BSD as early as 1987, and is standardized since
Y2K) removing such variables with unset will remove them also from
the environment, but in any way the knowledge they ever have been
linked will be lost. This implies that localopts may cause loss of
such links.
The subcommand unlink removes an existing link without otherwise
touching variables, the set and unset subcommands are identical to
set and unset, but additionally update the program environment
accordingly; removing a variable breaks any freely established
link.
errors
[Option] As console user interfaces at times scroll error messages
by too fast and/or out of scope, data can additionally be sent to
an error queue manageable by this command: show or no argument will
display and clear the queue, clear will only clear it. As the
queue becomes filled with errors-limit entries the eldest entries
are being dropped. There are also the variables ^ERRQUEUE-COUNT
and ^ERRQUEUE-EXISTS.
eval [Only new quoting rules] Construct a command by concatenating the
arguments, separated with a single space character, and then evalu-
ate the result. This command passes through the exit status ? and
error number ! of the evaluated command; also see call.
define xxx {
echo "xxx arg <$1>"
shift
if $# -gt 0
\xcall xxx "$@"
endif
}
define yyy {
eval "$@ ' ball"
}
call yyy '\call xxx' "b\$'\t'u ' "
call xxx arg <b u>
call xxx arg < >
call xxx arg <ball>
exit (ex or x) Exit from S-nail without changing the active mailbox and
skip any saving of messages in the secondary mailbox MBOX, as well
as a possibly tracked line editor history-file. A possibly set
on-account-cleanup will be invoked, however. The optional status
number argument will be passed through to exit(3). [v15 behaviour
may differ] For now it can happen that the given status will be
overwritten, later this will only occur if a later error needs to
be reported onto an otherwise success indicating status.
File (Fi) Like folder, but open the mailbox read-only.
file (fi) See folder.
filetype, unfiletype
[Only new quoting rules] Define, list, and remove, respectively,
file handler hooks, which provide (shell) commands that enable
S-nail to load and save MBOX files from and to files with the reg-
istered file extensions, as shown and described for folder. The
extensions are used case-insensitively, yet the auto-completion
feature of for example folder will only work case-sensitively. An
intermediate temporary file will be used to store the expanded
data. The latter command will remove hooks for all given exten-
sions, asterisk `*' will remove all existing handlers.
When used without arguments the former shows a list of all cur-
rently defined file hooks, with one argument the expansion of the
given alias. Otherwise three arguments are expected, the first
specifying the file extension for which the hook is meant, and the
second and third defining the load- and save commands to deal with
the file type, respectively, both of which must read from standard
input and write to standard output. Changing hooks will not affect
already opened mailboxes ([v15 behaviour may differ] except below).
[v15 behaviour may differ] For now too much work is done, and files
are oftened read in twice where once would be sufficient: this can
cause problems if a filetype is changed while such a file is
opened; this was already so with the built-in support of .gz etc.
in Heirloom, and will vanish in v15. [v15 behaviour may differ]
For now all handler strings are passed to the SHELL for evaluation
purposes; in the future a `!' prefix to load and save commands may
mean to bypass this shell instance: placing a leading space will
avoid any possible misinterpretations.
? filetype bz2 'bzip2 -dc' 'bzip2 -zc' \
gz 'gzip -dc' 'gzip -c' xz 'xz -dc' 'xz -zc' \
zst 'zstd -dc' 'zstd -19 -zc' \
zst.pgp 'gpg -d | zstd -dc' 'zstd -19 -zc | gpg -e'
? set record=+sent.zst.pgp
flag, unflag
Take message lists and mark the messages as being flagged, or not
being flagged, respectively, for urgent/special attention. See the
section Message states.
Folder
(Fold) Like folder, but open the mailbox read-only.
folder
(fold) Open a new, or show status information of the current mail-
box. If an argument is given, changes (such as deletions) will be
written out, a new mailbox will be opened, the internal variables
mailbox-resolved and mailbox-display will be updated, a set accord-
ing folder-hook is executed, and optionally a summary of headers is
displayed if the variable header is set.
Filename transformations will be applied to the name argument, and
`protocol://' prefixes are, i.e., URL (see On URL syntax and
credential lookup) syntax is understood, as in
`mbox:///tmp/somefolder'. If a protocol prefix is used the mailbox
type is fixated, otherwise opening none-existing folders uses the
protocol defined in newfolders.
For the protocols mbox and file (MBOX database), as well as eml
(electronic mail message [v15 behaviour may differ] read-only) the
list of all registered filetypes is traversed to check whether
hooks shall be used to load (and save) data from (and to) the given
name. Changing hooks will not affect already opened mailboxes.
For example, the following creates hooks for the gzip(1) compres-
sion tool and a combined compressed and encrypted format:
? filetype \
gzip 'gzip -dc' 'gzip -c' \
zst.pgp 'gpg -d | zstd -dc' 'zstd -19 -zc | gpg -e'
For historic reasons filetypes provide limited (case-sensitive)
auto-completion capabilities. For example `mbox.gz' will be found
for `? file mbox', provided that corresponding handlers are
installed. It will neither find `mbox.GZ' nor `mbox.Gz' however,
but an explicit `? file mbox.GZ' will find and use the handler for
`gz'. [v15 behaviour may differ] The latter mode can only be used
for MBOX files.
EML files consist of only one mail message, [v15 behaviour may dif-
fer] and can only be opened read-only. When reading MBOX files
tolerant POSIX rules are used by default. Invalid message bound-
aries that can be found quite often in historic MBOX files will be
complained about (even more with debug): in this case the method
described for mbox-rfc4155 can be used to create a valid MBOX data-
base from the invalid input.
MBOX databases and EML files will always be protected via file-
region locks (fcntl(2)) during file operations to protect against
concurrent modifications. [Option] An MBOX inbox (MAIL) or primary
system mailbox will also be protected by so-called dotlock files,
the traditional way of mail spool file locking: for any file `x' a
lock file `x.lock' will be created during the synchronization, in
the same directory and with the same user and group identities as
the file of interest -- as necessary created by an external privi-
leged dotlock helper. dotlock-disable disables dotlock files.
Also see FAQ: Howto handle stale dotlock files.
[Option] If no protocol has been fixated, and name refers to a
directory with the subdirectories `tmp', `new' and `cur', then it
is treated as a folder in ``Maildir'' format. The maildir format
stores each message in its own file, and has been designed so that
file locking is not necessary when reading or writing files.
[Option]ally URLs can be used to access network resources, securely
via Encrypted network communication, if so supported. Network com-
munication socket timeouts are configurable via
socket-connect-timeout. All network traffic may be proxied over a
SOCKS server via socks-proxy.
[v15-compat] protocol://[user[:password]@]host[:port][/path]
[no v15-compat] protocol://[user@]host[:port][/path]
[Option]ally supported network protocols are pop3 (POP3) and pop3s
(POP3 with TLS encrypted transport), imap and imaps. The [/path]
part is valid only for IMAP; there it defaults to INBOX. Network
URLs require a special encoding as documented in the section On URL
syntax and credential lookup.
folders
Lists the names of all folders below the given argument or folder.
For file-based protocols LISTER will be used for display purposes.
Followup, followup
(Compose mode)(F,fo) Similar to Reply, and reply, respectively, but
save the message in a file named after the local part of the
(first) recipient's address, possibly overwriting record, and hon-
ouring outfolder. Also see Copy and Save.
Forward
(Compose mode) Similar to forward, but saves the message in a file
named after the local part of the recipient's address (instead of
in record).
forward
(Compose mode) Take a message list and the address of a recipient,
subject to fullnames, to whom the messages are sent. The text of
the original message is included in the new one, enclosed by the
values of forward-inject-head and forward-inject-tail.
content-description-forwarded-message is inspected. The list of
included headers can be filtered with the `forward' slot of the
white- and blacklisting command headerpick. Only the first part of
a multipart message is included but for forward-as-attachment.
This may generate the errors ^ERR-DESTADDRREQ if no receiver has
been specified, or was rejected by expandaddr policy, ^ERR-IO if an
I/O error occurs, ^ERR-NOTSUP if a necessary character set conver-
sion fails, and ^ERR-INVAL for other errors. It can also fail with
errors of Specifying messages. Any error stops processing of fur-
ther messages.
from (f) Takes a list of message specifications and displays a summary
of their message headers, exactly as via headers, making the first
message of the result the new ``dot'' (the last message if showlast
is set). An alias of this command is search. Also see Specifying
messages.
Fwd [Obsolete] Alias for Forward.
fwd [Obsolete] Alias for forward.
fwdignore
[Obsolete] Superseded by the multiplexer headerpick.
fwdretain
[Obsolete] Superseded by the multiplexer headerpick.
ghost, unghost
[Obsolete] Replaced by commandalias, uncommandalias.
headerpick, unheaderpick
[Only new quoting rules] Multiplexer command to manage white- and
blacklisting selections of header fields for a variety of applica-
tions. Without arguments the set of contexts that have settings is
displayed. When given arguments, the first argument is the context
to which the command applies, one of (case-insensitive) `type' for
display purposes (for example type), `save' for selecting which
headers shall be stored persistently when save, copy, move or even
decrypting messages (note that MIME related etc. header fields
should not be ignored in order to not destroy usability of the mes-
sage in this case), `forward' for stripping down messages when
forwarding message (has no effect if forward-as-attachment is set),
and `top' for defining user-defined set of fields for the command
top.
The current settings of the given context are displayed if it is
the only argument. A second argument denotes the type of restric-
tion that is to be chosen, it may be (a case-insensitive prefix of)
`retain' or `ignore' for white- and blacklisting purposes, respec-
tively. Establishing a whitelist suppresses inspection of the cor-
responding blacklist.
If no further argument is given the current settings of the given
type will be displayed, otherwise the remaining arguments specify
header fields, which [Option]ally may be given as regular expres-
sions, to be added to the given type. The special wildcard field
(asterisk, `*') will establish a (fast) shorthand setting which
covers all fields.
The latter command always takes three or more arguments and can be
used to remove selections, i.e., from the given context, the given
type of list, all the given headers will be removed, the special
argument `*' will remove all headers.
headers
(h) Show the current group of headers, the size of which depends on
the variable screen in interactive mode, and the format of which
can be defined with headline. If a message-specification is given
the group of headers containing the first message therein is shown
and the message at the top of the screen becomes the new ``dot'';
the last message is targeted if showlast is set.
help (hel) A synonym for ?.
history
[Option] Without arguments or when given show all history entries
are shown (this mode also supports a more verbose output). load
will replace the list of entries with the content of history-file,
and save will dump all entries to said file, replacing former con-
tent, and clear will delete all entries. The argument can also be
a signed decimal NUMBER, which will select and evaluate the respec-
tive history entry, and move it to the top of the history; a nega-
tive number is used as an offset to the current command so that
`-1' will select the last command, the history top, whereas delete
will delete all given entries (:NUMBER:). Also see On terminal
control and line editor.
hold (ho, also preserve) Takes a message list and marks each message
therein to be saved in the user's system inbox instead of in the
secondary mailbox MBOX. Does not override the delete command.
S-nail deviates from the POSIX standard with this command, because
a next command issued after hold will display the following mes-
sage, not the current one.
if (i) Part of the if, elif, else, endif conditional execution con-
struct -- if the given condition is true then the encapsulated
block is executed. The POSIX standard only supports the (case-
insensitive) conditions `r'eceive and `s'end, the remaining are
non-portable extensions. [v15 behaviour may differ] In conjunction
with the wysh command prefix(es) Shell-style argument quoting and
more test operators are available.
if receive
commands ...
else
commands ...
endif
Further (case-insensitive) one-argument conditions are `t'erminal
which evaluates to true in interactive terminal sessions (running
with standard input or standard output attached to a terminal, and
none of the ``quickrun'' command line options -e, -H and -L have
been used), as well as any boolean value (see INTERNAL VARIABLES
for textual boolean representations) to mark an enwrapped block as
``never execute'' or ``always execute''. (Remarks: condition syn-
tax errors skip all branches until endif.)
[no v15-compat] and without wysh: It is possible to check INTERNAL
VARIABLES as well as ENVIRONMENT variables for existence or compare
their expansion against a user given value or another variable by
using the `$' (``variable next'') conditional trigger character; a
variable on the right hand side may be signalled using the same
mechanism. Variable names may be enclosed in a pair of matching
braces. When this mode has been triggered, several operators are
available ([v15-compat] and wysh: they are always available, and
there is no trigger: variables will have been expanded by the
shell-compatible parser before the if etc. command sees them).
[v15-compat] Two argument conditions. Variables can be tested for
existence and expansion: `-N' will test whether the given variable
exists, so that `-N editalong' will evaluate to true when editalong
is set, whereas `-Z editalong' will if it is not. `-n
"$editalong"' will be true if the variable is set and expands to a
non-empty string, `-z $'\$editalong'' only if the expansion is
empty, whether the variable exists or not. The remaining condi-
tions take three arguments.
Integer operators treat the arguments on the left and right hand
side of the operator as integral numbers and compare them arith-
metically. It is an error if any of the operands is not a valid
integer, an empty argument (which implies it had been quoted) is
treated as if it were 0. Via the question mark `?' modifier suffix
a saturated operation mode is available where numbers will linger
at the minimum or maximum possible value, instead of overflowing
(or trapping), the keyword `saturated' is optional, `==?',
`==?satu' and `==?saturated' are therefore identical. Available
operators are `-lt' (less than), `-le' (less than or equal to),
`-eq' (equal), `-ne' (not equal), `-ge' (greater than or equal to),
and `-gt' (greater than).
String and regular expression data operators compare the left and
right hand side according to their textual content. Unset vari-
ables are treated as the empty string. Via the question mark `?'
modifier suffix a case-insensitive operation mode is available, the
keyword `case' is optional, `==?' and `==?case' are identical.
Available string operators are `<' (less than), `<=' (less than or
equal to), `==' (equal), `!=' (not equal), `>=' (greater than or
equal to), `>' (greater than), `=%' (is substring of) and `!%' (is
not substring of). By default these operators work on bytes and
(therefore) do not take into account character set specifics. If
the case-insensitivity modifier has been used, case is ignored
according to the rules of the US-ASCII encoding, i.e., bytes are
still compared.
When the [Option]al regular expression support is available, the
additional string operators `=~' and `!~' can be used. They treat
the right hand side as an extended regular expression that is
matched according to the active locale (see Character sets), i.e.,
character sets should be honoured correctly.
Conditions can be joined via AND-OR lists (where the AND operator
is `&&' and the OR operator is `||'), which have equal precedence
and will be evaluated with left associativity, thus using the same
syntax that is known for the sh(1). It is also possible to form
groups of conditions and lists by enclosing them in pairs of brack-
ets `[ ... ]', which may be interlocked within each other, and also
be joined via AND-OR lists.
The results of individual conditions and entire groups may be modi-
fied via unary operators: the unary operator `!' will reverse the
result.
wysh set v15-compat=yes # with value: automatic "wysh"!
if -N debug;echo *debug* set;else;echo not;endif
if "$ttycharset" == UTF-8 || "$ttycharset" ==?cas UTF8
echo ttycharset is UTF-8, the former case-sensitive!
endif
set t1=one t2=one
if [ "${t1}" == "${t2}" ]
echo These two variables are equal
endif
if "$features" =% ,+regex, && "$TERM" =~?case ^xterm.*
echo ..in an X terminal
endif
if [ [ true ] && [ [ "${debug}" != '' ] || \
[ "$verbose" != '' ] ] ]
echo Noisy, noisy
endif
if true && [ -n "$debug" || -n "${verbose}" ]
echo Left associativity, as is known from the shell
endif
ignore
(ig) Identical to discard. Superseded by the multiplexer
headerpick.
list Shows the names of all available commands, in command lookup order.
[Option] In conjunction with a set variable verbose additional
information will be provided for each command: the argument type
will be indicated, the documentation string will be shown, and the
set of command flags will show up:
``local'' command supports the command modifier local.
``vput'' command supports the command modifier vput.
`*!*' the error number is tracked in !.
`needs-box' whether the command needs an active mailbox, a folder.
`ok:' indicators whether command is ...
`batch/interactive'
usable in interactive or batch mode
(-#).
`send-mode' usable in send mode.
`subprocess' allowed to be used when running in a
subprocess instance, for example from
within a macro that is called via
on-compose-splice.
`not ok:' indicators whether command is not ...
`compose mode' available in Compose mode.
`startup' available during program startup, like
in Resource files.
`gabby' The command produces history-gabby history entries.
localopts
Enforce change localization of environ (linked) ENVIRONMENT as well
as (global) INTERNAL VARIABLES, meaning that their state will be
reverted to the former one once the ``covered scope'' is left.
Just like the command modifier local, which provides block-scope
localization for some commands (instead), it can only be used
inside of macro definition blocks introduced by account or define.
The covered scope of an account is left once a different account is
activated, and some macros, notably folder-hooks, use their own
specific notion of covered scope, here it will be extended until
the folder is left again.
This setting stacks up: i.e., if `macro1' enables change localiza-
tion and calls `macro2', which explicitly resets localization, then
any value changes within `macro2' will still be reverted when the
scope of `macro1' is left. (Caveats: if in this example `macro2'
changes to a different account which sets some variables that are
already covered by localizations, their scope will be extended, and
in fact leaving the account will (thus) restore settings in
(likely) global scope which actually were defined in a local, macro
private context!)
This command takes one or two arguments, the optional first one
specifies an attribute that may be one of scope, which refers to
the current scope and is thus the default, call, which causes any
macro that is being called to be started with localization enabled
by default, as well as call-fixate, which (if enabled) disallows
any called macro to turn off localization: like this it can be
ensured that once the current scope regains control, any changes
made in deeper levels have been reverted. The latter two are mutu-
ally exclusive, and neither affects xcall. The (second) argument
is interpreted as a boolean (string, see INTERNAL VARIABLES) and
states whether the given attribute shall be turned on or off.
define temporary_settings {
set possibly_global_option1
localopts on
set localized_option1
set localized_option2
localopts scope off
set possibly_global_option2
}
Lfollowup, Lreply
(Compose mode) Reply to messages that come in via known (mlist) or
subscribed (mlsubscribe) mailing lists, or pretend to do so (see
Mailing lists): on top of the usual followup and reply, respec-
tively, functionality this will actively resort and even remove
message recipients in order to generate a message that is supposed
to be sent to a mailing list. For example it will also implicitly
generate a `Mail-Followup-To:' header if that seems useful, regard-
less of the setting of the variable followup-to. For more documen-
tation please refer to On sending mail, and non-interactive mode.
This may generate the errors ^ERR-DESTADDRREQ if no receiver has
been specified, ^ERR-PERM if some addressees where rejected by
expandaddr, ^ERR-IO if an I/O error occurs, ^ERR-NOTSUP if a neces-
sary character set conversion fails, and ^ERR-INVAL for other
errors. It can also fail with errors of Specifying messages.
Occurrence of some of the errors depend on the value of expandaddr.
Any error stops processing of further messages.
Mail (Compose mode) Similar to mail, but saves the message in a file
named after the local part of the first recipient's address
(instead of in record).
mail (Compose mode)(m) Takes a (list of) recipient address(es) as (an)
argument(s), or asks on standard input if none were given; then
collects the remaining mail content and sends it out. Unless the
internal variable fullnames is set recipient addresses will be
stripped from comments, names etc. For more documentation please
refer to On sending mail, and non-interactive mode.
This may generate the errors ^ERR-DESTADDRREQ if no receiver has
been specified, ^ERR-PERM if some addressees where rejected by
expandaddr, ^ERR-NOTSUP if multiple messages have been specified,
^ERR-IO if an I/O error occurs, ^ERR-NOTSUP if a necessary charac-
ter set conversion fails, and ^ERR-INVAL for other errors. It can
also fail with errors of Specifying messages. Occurrence of some
of the errors depend on the value of expandaddr.
mailcap
[Option] When used without arguments or if show has been given the
content of The Mailcap files cache is shown, (re-)initializing it
first (as necessary. If the argument is load then the cache will
only be (re-)initialized, and clear will remove its contents. Note
that S-nail will try to load the files only once, use `mailcap
clear' to unlock further attempts. Loading and parsing can be made
more verbose.
mbox (mb) The given message list is to be sent to the secondary mailbox
MBOX when S-nail is quit; this is the default action unless the
variable hold is set. [v15 behaviour may differ] This command can
only be used in a primary system mailbox.
mimetype, unmimetype
[Only new quoting rules] Without arguments the content of the MIME
type cache will displayed; a more verbose listing will be produced
if either of debug or verbose are set. When given arguments they
will be joined, interpreted as shown in The mime.types files (also
see HTML mail and MIME attachments), and the resulting entry will
be added (prepended) to the cache. In any event MIME type sources
are loaded first as necessary - mimetypes-load-control can be used
to fine-tune which sources are actually loaded.
The latter command deletes all specifications of the given MIME
type, thus `? unmimetype text/plain' will remove all registered
specifications for the MIME type `text/plain'. The special name
`*' will discard all existing MIME types, just as will `reset', but
which also reenables cache initialization via
mimetypes-load-control.
mimeview
[v15 behaviour may differ] Only available in interactive mode, this
command allows execution of external MIME type handlers which do
not integrate into the normal type output (see HTML mail and MIME
attachments). ([v15 behaviour may differ] No syntax to directly
address parts, this restriction may vanish.) The user will be
asked for each non-text part of the given message in turn whether
the registered handler shall be used to display the part.
mlist, unmlist
[Only new quoting rules] Manage the list of known Mailing lists;
subscriptions are controlled via mlsubscribe. The latter command
deletes all given arguments, or all at once when given the asterisk
`*'. The former shows the list of all currently known lists if
used without arguments, otherwise the given arguments will become
known. [Option] In the latter case, arguments which contain any of
the magic regular expression characters will be interpreted as one,
possibly matching many addresses; these will be sequentially
matched via linked lists instead of being looked up in a dictio-
nary.
mlsubscribe, unmlsubscribe
Building upon the command pair mlist, unmlist, but only managing
the subscription attribute of mailing lists. (The former will also
create not yet existing mailing lists.)
Move Similar to move, but move the messages to a file named after the
local part of the sender of the first message instead of taking a
filename argument; outfolder is inspected to decide on the actual
storage location.
move Acts like copy but marks the messages for deletion if they were
transferred successfully.
More Like more, but also displays header fields which would not pass the
headerpick selection, and all MIME parts. Identical to Page.
more Invokes the PAGER on the given messages, even in non-interactive
mode and as long as the standard output is a terminal. Identical
to page.
mtaaliases
[Option] When used without arguments or if show has been given the
content of the mta-aliases cache is shown, (re-)initializing it
first (as necessary). If the argument is load then the cache will
only be (re-)initialized, and clear will remove its contents.
netrc
[Option] When used without arguments, or when the argument was show
the content of the ~/.netrc cache is shown, initializing it as nec-
essary. If the argument is load then the cache will be (re)loaded,
whereas clear removes it. Loading and parsing can be made more
verbose. lookup will query the cache for the URL given as the sec-
ond argument (`[USER@]HOST'). See netrc-lookup, netrc-pipe and the
section On URL syntax and credential lookup; the section The .netrc
file documents the file format in detail.
newmail
Checks for new mail in the current folder without committing any
changes before. If new mail is present, a message is shown. If
the header variable is set, the headers of each new message are
also shown. This command is not available for all mailbox types.
next (n) (like `+' or ``ENTER'') Goes to the next message in sequence
and types it. With an argument list, types the next matching mes-
sage.
New Same as Unread.
new Same as unread.
noop If the current folder is accessed via a network connection, a
``NOOP'' command is sent, otherwise no operation is performed.
Page Like page, but also displays header fields which would not pass the
headerpick selection, and all MIME parts. Identical to More.
page Invokes the PAGER on the given messages, even in non-interactive
mode and as long as the standard output is a terminal. Identical
to more.
Pipe Like pipe but also pipes header fields which would not pass the
headerpick selection, and all parts of MIME `multipart/alternative'
messages.
pipe (pi) Takes an optional message list and shell command (that
defaults to cmd), and pipes the messages through the command. If
the page variable is set, every message is followed by a formfeed
character.
preserve
(pre) A synonym for hold.
Print
(P) Alias for Type.
print
(p) Research UNIX equivalent of type.
quit (q) Terminates the session, saving all undeleted, unsaved messages
in the current secondary mailbox MBOX, preserving all messages
marked with hold or preserve or never referenced in the system
inbox, and removing all other messages from the primary system
mailbox. If new mail has arrived during the session, the message
``You have new mail'' will be shown. If given while editing a
mailbox file with the command line option -f, then the edit file is
rewritten. A return to the shell is effected, unless the rewrite
of edit file fails, in which case the user can escape with the exit
command. The optional status number argument will be passed
through to exit(3). [v15 behaviour may differ] For now it can hap-
pen that the given status will be overwritten, later this will only
occur if a later error needs to be reported onto an otherwise suc-
cess indicating status.
read [Only new quoting rules] Read a line from standard input, or the
channel set active via readctl, and assign the data, which will be
split as indicated by ifs, to the given variables. The variable
names are checked by the same rules as documented for vput, and the
same error codes will be seen in !; the exit status ? indicates the
number of bytes read, it will be `-1' with the error number ! set
to ^ERR-BADF in case of I/O errors, or ^ERR-NONE upon End-Of-File.
If there are more fields than variables, assigns successive fields
to the last given variable. If there are less fields than vari-
ables, assigns the empty string to the remains.
? read a b c
H e l l o
? echo "<$a> <$b> <$c>"
<H> <e> <l l o>
? wysh set ifs=:; read a b c;unset ifs
hey2.0,:"'you ",:world!:mars.:
? echo $?/$^ERRNAME / <$a><$b><$c>
0/NONE / <hey2.0,><"'you ",><world!:mars.:><><>
readsh
[Only new quoting rules] Like read, but splits on shell token
boundaries (see Shell-style argument quoting) rather than at ifs.
[v15 behaviour may differ] Could become a commandalias, maybe `read
--tokenize --'.
readall
[Only new quoting rules] Read anything from standard input, or the
channel set active via readctl, and assign the data to the given
variable. The variable name is checked by the same rules as docu-
mented for vput, and the same error codes will be seen in !; the
exit status ? indicates the number of bytes read, it will be `-1'
with the error number ! set to ^ERR-BADF in case of I/O errors, or
^ERR-NONE upon End-Of-File. [v15 behaviour may differ] The input
data length is restricted to 31-bits.
readctl
[Only new quoting rules] Manages input channels for read, readsh
and readall, to be used to avoid complicated or impracticable code,
like calling read from within a macro in non-interactive mode.
Without arguments, or when the first argument is show, a listing of
all known channels is printed. Channels can otherwise be created,
and existing channels can be set active and removed by giving the
string used for creation.
The channel name is expected to be a file descriptor number, or, if
parsing the numeric fails, an input file name that undergoes
Filename transformations. For example (this example requires a
modern shell):
$ printf 'echon "hey, "\nread a\nyou\necho $a' |\
s-nail -R#
hey, you
$ LC_ALL=C printf 'echon "hey, "\nread a\necho $a' |\
LC_ALL=C 6<<< 'you' s-nail -R#X'readctl create 6'
hey, you
remove
[Only new quoting rules] Removes the named files or directories.
If a name refers to a mailbox, say a Maildir mailbox, then a mail-
box type specific removal will be performed, deleting the complete
mailbox. In interactive mode the user is asked for confirmation.
rename
[Only new quoting rules] Takes the name of an existing folder and
the name for the new folder and renames the first to the second
one. Filename transformations including shell pathname wildcard
pattern expansions (glob(7)) are performed on both arguments. Both
folders must be of the same type.
Reply, Respond
(Compose mode)(R) Identical to reply except that it replies to only
the sender of each message of the given list, by using the first
message as the template to quote, for the `Subject:' etc.; setting
flipr will exchange this command with reply.
reply, respond
(Compose mode)(r) Take a message (list) and group-respond (to each
in turn) by addressing the sender and all recipients, subject to
fullnames and alternates processing. followup-to,
followup-to-honour, reply-to-honour as well as recipients-in-cc
influence response behaviour. quote as well as quote-as-attachment
configure whether responded-to message shall be quoted etc.,
content-description-quote-attachment may be used. Setting flipr
will exchange this command with Reply. The command Lreply offers
special support for replying to mailing lists. For more documenta-
tion please refer to On sending mail, and non-interactive mode.
This may generate the errors ^ERR-DESTADDRREQ if no receiver has
been specified, or was rejected by expandaddr policy, ^ERR-IO if an
I/O error occurs, ^ERR-NOTSUP if a necessary character set conver-
sion fails, and ^ERR-INVAL for other errors. It can also fail with
errors of Specifying messages. Any error stops processing of fur-
ther messages.
Resend
Like resend, but does not add any header lines. This is not a way
to hide the sender's identity, but useful for sending a message
again to the same recipients.
resend
Takes a list of messages and a name, and sends each message to the
given addressee, which is subject to fullnames. `Resent-From:' and
related header fields are prepended to the new copy of the message.
Saving in record is only performed if record-resent is set. [v15
behaviour may differ](Compose mode) is not entered, the only sup-
ported hooks are on-resend-enter and on-resend-cleanup.
This may generate the errors ^ERR-DESTADDRREQ if no receiver has
been specified, or was rejected by expandaddr policy, ^ERR-IO if an
I/O error occurs, ^ERR-NOTSUP if a necessary character set conver-
sion fails, and ^ERR-INVAL for other errors. It can also fail with
errors of Specifying messages. Any error stops processing of fur-
ther messages.
retain
(ret) Superseded by the multiplexer headerpick.
return
Only available inside of a defined macro or an account, this com-
mand returns control of execution to the outer scope. The two
optional parameters are positive decimal numbers and default to 0:
the first specifies the 32-bit return value (stored in ? [v15 be-
haviour may differ] and later extended to 64-bit), the second the
32-bit error number (stored in !). As documented for ? a non-0
exit status may cause the program to exit.
Save (S) Similar to save, but saves the messages in a file named after
the local part of the sender of the first message instead of taking
a filename argument; outfolder is inspected to decide on the actual
storage location.
save (s) Takes a message list and a filename and appends each message in
turn to the end of the file. Filename transformations including
shell pathname wildcard pattern expansions (glob(7)) is performed
on the filename. If no filename is given, the secondary mailbox
MBOX is used. The filename in quotes, followed by the generated
character count is echoed on the user's terminal. If editing a
primary system mailbox the messages are marked for deletion. To
filter the saved header fields to the desired subset use the `save'
slot of the white- and blacklisting command headerpick. Also see
Copy.
savediscard
[Obsolete] Superseded by the multiplexer headerpick.
saveignore
[Obsolete] Superseded by the multiplexer headerpick.
saveretain
[Obsolete] Superseded by the multiplexer headerpick.
search
Takes a message specification (list) and displays a header summary
of all matching messages, as via headers. This command is an alias
of from. Also see Specifying messages.
seen Takes a message list and marks all messages as having been read.
set, unset
(se, [Only new quoting rules] uns) The latter command will delete
all given global variables, or only block-scope local ones if the
local command modifier has been used. The former, when used with-
out arguments, will show all currently known variables, being more
verbose if either of debug or verbose is set. Remarks: this list
mode will not automatically link-in (known) ENVIRONMENT variables,
this only happens for explicit addressing, examples are varshow,
using a variable in an if condition or a string passed to echo,
explicit setting, as well as some program-internal use cases (look-
ups).
Otherwise the given variables (and arguments) are set or adjusted.
Arguments are of the form `name=value' (no space before or after
`='), or plain `name' if there is no value, i.e., a boolean vari-
able. If a name begins with `no', as in `set nosave', the effect
is the same as invoking the unset command with the remaining part
of the variable (`unset save'). [v15 behaviour may differ] In con-
junction with the wysh (or local) command prefix(es) Shell-style
argument quoting can be used to quote arguments as necessary. [v15
behaviour may differ] Otherwise quotation marks may be placed
around any part of the assignment statement to quote blanks or
tabs.
When operating in global scope any `name' that is known to map to
an environment variable will automatically cause updates in the
program environment (unsetting a variable in the environment
requires corresponding system support) -- use the command environ
for further environmental control. If the command modifier local
has been used to enforce local scoping then the given user vari-
ables will be garbage collected when the local scope is left; for
INTERNAL VARIABLES, however, local behaves the same as if localopts
would have been set (temporarily), which means that changes are
inherited by deeper scopes. Also see varshow and the sections
INTERNAL VARIABLES and ENVIRONMENT.
? wysh set indentprefix=' -> '
? wysh set atab=$'' aspace=' ' zero=0
shcodec
Apply shell quoting rules to the given raw-data arguments. Sup-
ports vput (see Command modifiers). The first argument specifies
the operation: [+]e[ncode] or d[ecode] cause shell quoting to be
applied to the remains of the line, and expanded away thereof,
respectively. If the former is prefixed with a plus-sign, the
quoted result will not be roundtrip enabled, and thus can be
decoded only in the very same environment that was used to perform
the encode; also see mle-quote-rndtrip. If the coding operation
fails the error number ! is set to ^ERR-CANCELED, and the unmodi-
fied input is used as the result; the error number may change again
due to output or result storage errors.
shell
[Only new quoting rules] (sh) Invokes an interactive version of the
shell, and returns its exit status.
shortcut, unshortcut
[Only new quoting rules] Manage the file- or pathname shortcuts as
documented for folder. The latter command deletes all shortcuts
given as arguments, or all at once when given the asterisk `*'.
The former shows the list of all currently defined shortcuts if
used without arguments, the target of the given with a single argu-
ment. Otherwise arguments are treated as pairs of shortcuts and
their desired expansion, creating new or updating already existing
ones.
shift
[Only new quoting rules] Shift the positional parameter stack
(starting at 1) by the given number (which must be a positive deci-
mal), or 1 if no argument has been given. It is an error if the
value exceeds the number of positional parameters. If the given
number is 0, no action is performed, successfully. The stack as
such can be managed via vpospar. Note this command will fail in
account and hook macros unless the positional parameter stack has
been explicitly created in the current context via vpospar.
show Like type, but performs neither MIME decoding nor decryption, so
that the raw message text is shown.
size (si) Shows the size in characters of each message of the given mes-
sage list.
sleep
[Only new quoting rules] Sleep for the specified number of seconds
(and optionally milliseconds), by default interruptible. If a
third argument is given the sleep will be uninterruptible, other-
wise the error number ! will be set to ^ERR-INTR if the sleep has
been interrupted. The command will fail and the error number will
be ^ERR-OVERFLOW if the given duration(s) overflow the time
datatype, and ^ERR-INVAL if the given durations are no valid inte-
gers.
sort, unsort
The latter command disables sorted or threaded mode, returns to
normal message order and, if the header variable is set, displays a
header summary. The former command shows the current sorting cri-
terion when used without an argument, but creates a sorted repre-
sentation of the current folder otherwise, and changes the next
command and the addressing modes such that they refer to messages
in the sorted order. Message numbers are the same as in regular
mode. If the header variable is set, a header summary in the new
order is also displayed. Automatic folder sorting can be enabled
by setting the autosort variable, as in `set autosort=thread'.
Possible sorting criterions are:
date Sort the messages by their `Date:' field, that is by the
time they were sent.
from Sort messages by the value of their `From:' field, that is
by the address of the sender. If the showname variable is
set, the sender's real name (if any) is used.
size Sort the messages by their size.
spam [Option] Sort the message by their spam score, as has been
classified by spamrate.
status Sort the messages by their message status.
subject Sort the messages by their subject.
thread Create a threaded display.
to Sort messages by the value of their `To:' field, that is
by the address of the recipient. If the showname variable
is set, the recipient's real name (if any) is used.
source
[Only new quoting rules] (so) The source command reads commands
from the given file. Filename transformations will be applied. If
the given expanded argument ends with a vertical bar `|' then the
argument will instead be interpreted as a shell command and S-nail
will read the output generated by it. Dependent on the settings of
posix and errexit, and also dependent on whether the command modi-
fier ignerr had been used, encountering errors will stop sourcing
of the given input. [v15 behaviour may differ] Note that source
cannot be used from within macros that execute as folder-hooks or
accounts, i.e., it can only be called from macros that were called.
source_if
[Only new quoting rules] The difference to source (beside not sup-
porting pipe syntax aka shell command input) is that this command
will not generate an error nor warn if the given file argument can-
not be opened successfully.
spamclear
[Option] Takes a list of messages and clears their `is-spam' flag.
spamforget
[Option] Takes a list of messages and causes the spam-interface to
forget it has ever used them to train its Bayesian filter. Unless
otherwise noted the `is-spam' flag of the message is inspected to
chose whether a message shall be forgotten to be ``ham'' or
``spam''.
spamham
[Option] Takes a list of messages and informs the Bayesian filter
of the spam-interface that they are ``ham''. This also clears the
`is-spam' flag of the messages in question.
spamrate
[Option] Takes a list of messages and rates them using the config-
ured spam-interface, without modifying the messages, but setting
their `is-spam' flag as appropriate; because the spam rating head-
ers are lost the rate will be forgotten once the mailbox is left.
Refer to the manual section Handling spam for the complete picture
of spam handling in S-nail.
spamset
[Option] Takes a list of messages and sets their `is-spam' flag.
spamspam
[Option] Takes a list of messages and informs the Bayesian filter
of the spam-interface that they are ``spam''. This also sets the
`is-spam' flag of the messages in question.
thread
[Obsolete] The same as `sort thread' (consider using a
`commandalias' as necessary).
tls [Only new quoting rules] TLS information and management command
multiplexer to aid in Encrypted network communication, mostly
available only if the term `,+sockets,' is included in features.
Commands support vput if so documented (see Command modifiers).
The result that is shown in case of errors is always the empty
string, errors can be identified via the error number !. For exam-
ple, string length overflows are caught and set ! to ^ERR-OVERFLOW.
The TLS configuration is honoured, especially tls-verify.
? vput tls result fingerprint pop3s://ex.am.ple
? echo $?/$!/$^ERRNAME: $result
certchain Show the complete verified peer certificate chain.
Includes informational fields in conjunction with
verbose.
certificate Show only the peer certificate, without any signers.
Includes informational fields in conjunction with
verbose.
fingerprint Show the tls-fingerprint-digested fingerprint of the
certificate of the given HOST (`server:port', where the
port defaults to the HTTPS port, 443). tls-fingerprint
is actively ignored for the runtime of this command.
Top Like top but always uses the headerpick `type' slot for white- and
blacklisting header fields.
top (to) Takes a message list and types out the first toplines lines of
each message on the user's terminal. Unless a special selection
has been established for the `top' slot of the headerpick command,
the only header fields that are displayed are `From:', `To:',
`Cc:', and `Subject:'. Top will always use the `type' headerpick
selection instead. It is possible to apply compression to what is
displayed by setting topsqueeze. Messages are decrypted and con-
verted to the terminal character set if necessary.
touch
(tou) Takes a message list and marks the messages for saving in the
secondary mailbox MBOX. S-nail deviates from the POSIX standard
with this command, as a following next command will display the
following message instead of the current one.
Type (T) Like type but also displays header fields which would not pass
the headerpick selection, and all visualizable parts of MIME
`multipart/alternative' messages.
type (t) Takes a message list and types out each message on the user's
terminal. The display of message headers is selectable via
headerpick. For MIME multipart messages, all parts with a content
type of `text', all parts which have a registered MIME type handler
(see HTML mail and MIME attachments) which produces plain text out-
put, and all `message' parts are shown, others are hidden except
for their headers. Messages are decrypted and converted to the
terminal character set if necessary. The command mimeview can be
used to display parts which are not displayable as plain text.
unaccount
See account.
unalias
(una) See alias.
unanswered
See answered.
unbind
See bind.
uncollapse
See collapse.
uncolour
See colour.
undefine
See define.
undelete
See delete.
undraft
See draft.
unflag
See flag.
unfwdignore
[Obsolete] Superseded by the multiplexer headerpick.
unfwdretain
[Obsolete] Superseded by the multiplexer headerpick.
unignore
Superseded by the multiplexer headerpick.
unmimetype
See mimetype.
unmlist
See mlist.
unmlsubscribe
See mlsubscribe.
Unread
Same as unread.
unread
Takes a message list and marks each message as not having been
read.
unretain
Superseded by the multiplexer headerpick.
unsaveignore
[Obsolete] Superseded by the multiplexer headerpick.
unsaveretain
[Obsolete] Superseded by the multiplexer headerpick.
unset
[Only new quoting rules] (uns) See set.
unshortcut
See shortcut.
unsort
See short.
unthread
[Obsolete] Same as unsort.
urlcodec
Perform URL percent codec operations on the raw-data argument,
rather according to RFC 3986. The first argument specifies the
operation: e[ncode] or d[ecode] perform plain URL percent en- and
decoding, respectively. p[ath]enc[ode] and p[ath]dec[ode] perform
a slightly modified operation which should be better for pathnames:
it does not allow a tilde `~', and will neither accept hyphen-minus
`-' nor dot `'. as an initial character. The remains of the line
form the URL data which is to be converted. This is a character
set agnostic operation, and it may thus decode bytes which are
invalid in the current ttycharset.
Supports vput (see Command modifiers), and manages the error number
!. If the coding operation fails the error number ! is set to
^ERR-CANCELED, and the unmodified input is used as the result; the
error number may change again due to output or result storage
errors. [v15 behaviour may differ] This command does not know
about URLs beside what is documented. (vexpr offers a makeprint
subcommand, shall the URL be displayed.)
varshow
[Only new quoting rules] This command produces the same output as
the listing mode of set, including verboseity adjustments, but only
for the given variables.
verify
[Option] Takes a message list and verifies each message. If a mes-
sage is not a S/MIME signed message, verification will fail for it.
The verification process checks if the message was signed using a
valid certificate, if the message sender's email address matches
one of those contained within the certificate, and if the message
content has been altered.
version
Shows the version and features of S-nail, optionally in a more
verbose form which also includes the build and running system envi-
ronment. This command supports vput (see Command modifiers).
vexpr
[Only new quoting rules] A multiplexer command which offers signed
64-bit numeric calculations, as well as other, mostly string-based
operations. C-style byte string operations are available via csop.
The first argument defines the number, type, and meaning of the
remaining arguments. An empty number argument is treated as 0.
Supports vput (see Command modifiers). The result shown in case of
errors is `-1' for usage errors and numeric operations, the empty
string otherwise; ``soft'' errors, like when a search operation
failed, will also set the ! error number to ^ERR-NODATA. Except
when otherwise noted numeric arguments are parsed as signed 64-bit
numbers, and errors will be reported in the error number ! as the
numeric error ^ERR-RANGE.
Numeric operations work on one or two signed 64-bit integers. Num-
bers prefixed with `0x' or `0X' are interpreted as hexadecimal
(base 16) numbers, whereas `0' indicates octal (base 8), and `0b'
as well as `0B' denote binary (base 2) numbers. It is possible to
use any base in between 2 and 36, inclusive, with the `BASE#number'
notation, where the base is given as an unsigned decimal number, so
`16#AFFE' is a different way of specifying a hexadecimal number.
Unsigned interpretation of a number can be enforced by prefixing an
`u' (case-insensitively), as in `u-110'; this is not necessary for
power-of-two bases (2, 4, 8, 16 and 32), which will be interpreted
as unsigned by default, but it still makes a difference regarding
overflow detection and overflow constant. It is possible to
enforce signed interpretation by (instead) prefixing a `s' (case-
insensitively). The number sign notation uses a permissive parse
mode and as such supports complicated conditions out of the box:
? wysh set ifs=:;read i;unset ifs;echo $i;vexpr pb 2 10#$i
-009
< -009>
0b1001
One integer is expected by assignment (equals sign `='), which does
nothing but parsing the argument, thus detecting validity and pos-
sible overflow conditions, unary not (tilde `~'), which creates the
bitwise complement, and unary plus and minus. Two integers are
used by addition (plus sign `+'), subtraction (hyphen-minus `-'),
multiplication (asterisk `*'), division (solidus `/') and modulo
(percent sign `%'), as well as for the bitwise operators logical or
(vertical bar `|', to be quoted) , bitwise and (ampersand `&', to
be quoted) , bitwise xor (circumflex `^'), the bitwise signed left-
and right shifts (`<<', `>>'), as well as for the unsigned right
shift `>>>'.
Another numeric operation is pbase, which takes a number base in
between 2 and 36, inclusive, and will act on the second number
given just the same as what equals sign `=' does, but the number
result will be formatted in the base given, as a signed 64-bit num-
ber unless unsigned interpretation of the input number had been
forced (with an u prefix).
Numeric operations support a saturated mode via the question mark
`?' modifier suffix; the keyword `saturated' is optional, `+?',
`+?satu', and `+?saturated' are therefore identical. In saturated
mode overflow errors and division and modulo by zero are no longer
reported via the exit status, but the result will linger at the
minimum or maximum possible value, instead of overflowing (or trap-
ping). This is true also for the argument parse step. For the
bitwise shifts, the saturated maximum is 63. Any caught overflow
will be reported via the error number ! as ^ERR-OVERFLOW.
? vput vexpr res -? +1 -9223372036854775808
? echo $?/$!/$^ERRNAME:$res
0/75/OVERFLOW:-9223372036854775808
Character set agnostic string functions have no notion of locale
settings and character sets.
date-utc Outputs the current date and time in UTC (Coordinated
Universal Time) with values named such that `vput vexpr x
date-utc; eval wysh set $x' creates accessible variables.
date-stamp-utc Outputs a RFC 3339 internet date/time format of UTC.
epoch The seconds and nanoseconds since the Unix epoch
(1970-01-01T00:00:00) named `epoch_sec' and `epoch_nsec'
such that `vput vexpr x epoch; eval wysh set $x' creates
accessible variables.
file-expand Performs the usual Filename transformations on its
argument.
file-stat, file-lstat Perform the usual Filename transformations on
the argument, then call stat(2) and lstat(2), respec-
tively, and output values such that `vput vexpr x
file-stat FILE; eval wysh set $x' creates accessible
variables. The variable `st_type' uses solidus `/' to
denote directories, commercial at `@' for links, number
sign `#' for block devices, percent sign `%' for for
character devices, vertical bar `|' for FIFOs, equal sign
`=' for sockets, and the period `.' for the rest.
random Generates a random string of the given length, or of
PATH_MAX bytes (a constant from /usr/include) if the
value 0 is given; the random string will be base64url
encoded according to RFC 4648, and thus be usable as a
(portable) filename.
String operations work, sufficient support provided, according to
the active user's locale encoding and character set (see Character
sets). Where the question mark `?' modifier suffix is supported, a
case-insensitive operation mode is available; the keyword `case' is
optional, `regex?' and `regex?case' are therefore identical.
makeprint (One-way) Converts the argument to something safely
printable on the terminal.
regex [Option] A string operation that will try to match the
first argument with the regular expression given as the
second argument. `?' modifier suffix is supported. If
the optional third argument has been given then instead
of showing the match offset a replacement operation is
performed: the third argument is treated as if specified
within dollar-single-quote (see Shell-style argument
quoting), and any occurrence of a positional parameter,
for example 0, 1 etc. is replaced with the according
match group of the regular expression:
? vput vexpr res regex bananarama \
(.*)NanA(.*) '\${1}au\$2'
? echo $?/$!/$^ERRNAME:$res:
1/61/NODATA::
? vput vexpr res regex?case bananarama \
(.*)NanA(.*) '\${1}uauf\$2'
? echo $?/$!/$^ERRNAME:$res:
0/0/NONE:bauauframa:
vpospar
[Only new quoting rules] Manage the positional parameter stack (see
1, #, *, @ as well as shift). If the first argument is `clear',
then the positional parameter stack of the current context, or the
global one, if there is none, is cleared. If it is `set', then the
remaining arguments will be used to (re)create the stack, if the
parameter stack size limit is excessed an ^ERR-OVERFLOW error will
occur.
If the first argument is `quote', a round-trip capable representa-
tion of the stack contents is created, with each quoted parameter
separated from each other with the first character of ifs, and fol-
lowed by the first character of if-ws, if that is not empty and not
identical to the first. If that results in no separation at all a
space character is used. This mode supports vput (see Command
modifiers). I.e., the subcommands `set' and `quote' can be used
(in conjunction with eval) to (re)create an argument stack from and
to a single variable losslessly.
? vpospar set hey, "'you ", world!
? echo $#: <${1}><${2}><${3}>
? vput vpospar x quote
? vpospar clear
? echo $#: <${1}><${2}><${3}>
? eval vpospar set ${x}
? echo $#: <${1}><${2}><${3}>
visual
(v) Takes a message list and invokes the VISUAL display editor on
each message. Modified contents are discarded unless the
writebackedited variable is set, and are not used unless the mail-
box can be written to and the editor returns a successful exit sta-
tus. edit can be used instead for a less display oriented editor.
write
(w) For conventional messages the body without all headers is writ-
ten. The original message is never marked for deletion in the
originating mail folder. The output is decrypted and converted to
its native format as necessary. If the output file exists, the
text is appended. If a message is in MIME multipart format its
first part is written to the specified file as for conventional
messages, handling of the remains depends on the execution mode.
No special handling of compressed files is performed.
In interactive mode the user is consecutively asked for the file-
names of the processed parts. For convenience saving of each part
may be skipped by giving an empty value, the same result as writing
it to /dev/null. Shell piping the part content by specifying a
leading vertical bar `|' character for the filename is supported.
Other user input undergoes the usual Filename transformations,
including shell pathname wildcard pattern expansions (glob(7)) and
shell variable expansion for the message as such, not the individ-
ual parts, and contents of the destination file are overwritten if
the file previously existed. Character set conversion to
ttycharset is performed when saving text data.
[v15 behaviour may differ] In non-interactive mode any part which
does not specify a filename is ignored, and suspicious parts of
filenames of the remaining parts are URL percent encoded (as via
urlcodec) to prevent injection of malicious character sequences,
resulting in a filename that will be written into the current
directory. Existing files will not be overwritten, instead the
part number or a dot are appended after a number sign `#' to the
name until file creation succeeds (or fails due to other reasons).
xcall
[Only new quoting rules] The sole difference to call is that the
new macro is executed in place of the current one, which will not
regain control: all resources of the current macro will be released
first. This implies that any setting covered by localopts will be
forgotten and covered variables will become cleaned up. If this
command is not used from within a called macro it will silently be
(a more expensive variant of) call.
xit (x) A synonym for exit.
z [Only new quoting rules] S-nail presents message headers in
screenfuls as described under the headers command. Without argu-
ments this command scrolls to the next window of messages, likewise
if the argument is `+'. An argument of `-' scrolls to the last,
`^' scrolls to the first, and `$' to the last screen of messages.
A number argument prefixed by `+' or `-' indicates that the window
is calculated in relation to the current position, and a number
without a prefix specifies an absolute position.
Z [Only new quoting rules] Similar to z, but scrolls to the next or
previous window that contains at least one `new' or flagged mes-
sage.
COMMAND ESCAPES
Command escapes are available in Compose mode during interactive usage,
when explicitly requested via -~, and in batch mode (-#). They perform
special functions, like editing headers of the message being composed,
calling normal COMMANDS, yielding a shell, etc. Command escapes are only
recognized at the beginning of lines, and consist of an escape followed
by a command character. The default escape character is the tilde `~'.
Unless otherwise documented command escapes ensure proper updates of the
error number ! and the exit status ?. The variable errexit controls
whether a failed operation errors out message compose mode and causes
program exit. Escapes may be prefixed by none to multiple single charac-
ter command modifiers, interspersed whitespace is ignored:
o An effect equivalent to the command modifier ignerr can be achieved
with hyphen-minus `-', overriding errexit.
o The modifier dollar `$' evaluates the remains of the line; also see
Shell-style argument quoting. [v15 behaviour may differ] For now the
entire input line is evaluated as a whole; to avoid that control
operators like semicolon ; are interpreted unintentionally, they must
be quoted.
Addition of the command line to the [Option]al history can be prevented
by placing whitespace directly after escape. The [Option]al key bindings
support a compose mode specific context. The following command escapes
are supported:
~~ string
Insert the string of text in the message prefaced by a single `~'.
(If the escape character has been changed, that character must be
doubled instead.)
~! command
Execute the indicated shell command which follows, replacing
unescaped exclamation marks with the previously executed command if
the internal variable bang is set, then return to the message.
~. End compose mode and send the message. The hooks
on-compose-splice-shell and on-compose-splice, in order, will be
called when set, after which, in interactive mode askatend (leading
to askcc, askbcc) and askattach will be checked as well as asksend,
after which a set on-compose-leave hook will be called, autocc and
autobcc will be joined in if set, finally a given
message-inject-tail will be incorporated, after which the compose
mode is left.
~: S-nail-command or ~_ S-nail-command
Can be used to execute COMMANDS (which are allowed in compose
mode).
~< filename
Identical to ~r.
~<! command
command is executed using the shell. Its standard output is
inserted into the message.
~? [Option] Write a summary of command escapes.
~@ [filename...]
Append or edit the list of attachments. Does not manage the error
number ! and the exit status ? (please use ~^ if error handling is
necessary). The append mode expects a list of filename arguments
as shell tokens (see Shell-style argument quoting; token-separating
commas are ignored, too), to be interpreted as documented for the
command line option -a, with the message number exception as below.
Without filename arguments the attachment list is edited, entry by
entry; if a filename is left empty, that attachment is deleted from
the list; once the end of the list is reached either new attach-
ments may be entered or the session can be quit by committing an
empty ``new'' attachment. In non-interactive mode or in batch mode
(-#) the list of attachments is effectively not edited but instead
recreated; again, an empty input ends list creation.
For all modes, if a given filename solely consists of the number
sign `#' followed by either a valid message number of the currently
active mailbox, or by a period `.', referring to the current mes-
sage of the active mailbox, the so-called ``dot'', then the given
message is attached as a `message/rfc822' MIME message part. The
number sign must be quoted to avoid misinterpretation as a shell
comment character.
~| command
Pipe the message text through the specified filter command. If the
command gives no output or terminates abnormally, retain the origi-
nal text of the message. The command fmt(1) is often used as a
rejustifying filter.
If the first character of the command is a vertical bar, then the
entire message including header fields is subject to the filter
command, so `~|| echo Fcc: /tmp/test; cat' will prepend a file-car-
bon-copy message header. Also see ~e, ~v.
~^ cmd [subcmd [arg3 [arg4]]]
Inspect and modify the message using the semantics of digmsg,
therefore arguments are evaluated according to Shell-style argument
quoting. Error number ! and exit status ? are not managed: errors
are handled via the protocol, and hard errors like I/O failures
cannot be handled.
The protocol consists of command lines followed by (a) response
line(s). The first field of the response line represents a status
code which specifies whether a command was successful or not,
whether result data is to be expected, and if, the format of the
result data. Response data will be shell quoted as necessary for
consumption by readsh, or eval and vpospar, to name a few. Error
status code lines may optionally contain additional context:
`210' Status ok; the remains of the line are the result.
`211' Status ok; the rest of the line is optionally used for more
status. What follows are lines of result addresses, termi-
nated by an empty line. All the input, including the empty
line, must be consumed before further commands can be
issued. Address lines consist of two token, first the plain
network address, e.g., `bob AT exam.ple', followed by the
(quoted) full address as known: `'(Lovely) Bob
<bob AT exam.ple>''. Non-network addresses use the first field
to indicate the type (hyphen-minus `-' for files, vertical
bar `|' for pipes, and number sign `#' for names which will
undergo alias processing) instead, the actual value will be
in the second field.
`212' Status ok; the rest of the line is optionally used for more
status. What follows are lines of furtherly unspecified
(quoted) string content, terminated by an empty line. All
the input, including the empty line, must be consumed before
further commands can be issued.
`500' Syntax error; invalid command.
`501' Syntax error or otherwise invalid parameters or arguments.
`505' Error: an argument fails verification. For example an
invalid address has been specified (also see expandaddr), or
an attempt was made to modify anything in S-nail's own
namespace, or a modifying subcommand has been used on a
read-only message.
`506' Error: an otherwise valid argument is rendered invalid due
to context. For example, a second address is added to a
header which may consist of a single address only.
If a command indicates failure then the message will have remained
unmodified. Most commands can fail with `500' if required argu-
ments are missing, or excessive arguments have been given (false
command usage). ([v15 behaviour may differ] The latter does not
yet occur regularly, because as stated in Shell-style argument
quoting our argument parser is not yet smart enough to work on sub-
command base; for example one might get excess argument error for a
three argument subcommand that receives four arguments, but not for
a four argument subcommand which receives six arguments: here
excess will be joined.) The following (case-insensitive) commands
are supported:
attachment This command allows listing, removal and addition of
message attachments. The second argument specifies the
subcommand to apply, one of:
attribute This uses the same search mechanism as described
for remove and prints any known attributes of
the first found attachment via `212' upon suc-
cess or `501' if no such attachment can be
found. The attributes are written as lines with
a keyword and a value token.
attribute-at This uses the same search mechanism as
described for remove-at and is otherwise identi-
cal to attribute.
attribute-set This uses the same search mechanism as
described for remove, and will set the attribute
given as the fourth to the value given as the
fifth token argument. If the value is an empty
token, then the given attribute is removed, or
reset to a default value if existence of the
attribute is crucial.
It returns via `210' upon success, with the
index of the found attachment following, `505'
for message attachments or if the given keyword
is invalid, and `501' if no such attachment can
be found. The following keywords may be used
(case-insensitively):
`filename' Sets the filename of the MIME part,
i.e., the name that is used for dis-
play and when (suggesting a name
for) saving (purposes).
`content-description' Associate some descriptive
information to the attachment's con-
tent, used in favour of the plain
filename by some MUAs.
`content-id' May be used for uniquely identify-
ing MIME entities in several con-
texts; this expects a special refer-
ence address format as defined in
RFC 2045 and generates a `505' upon
address content verification fail-
ure.
`content-type' Defines the media type/subtype of
the part, which is managed automati-
cally, but can be overwritten.
`content-disposition' Automatically set to the
string `attachment'.
attribute-set-at This uses the same search mechanism as
described for remove-at and is otherwise identi-
cal to attribute-set.
insert Adds the attachment given as the third argument,
specified exactly as documented for the command
line option -a, and supporting the message num-
ber extension as documented for ~@. This
reports `210' upon success, with the index of
the new attachment following, `505' if the given
file cannot be opened, `506' if an on-the-fly
performed character set conversion fails, other-
wise `501' is reported; this is also reported if
character set conversion is requested but not
available.
list List all attachments via `212', or report `501'
if no attachments exist. This command is the
default command of attachment if no second argu-
ment has been given.
remove This will remove the attachment given as the
third argument, and report `210' upon success or
`501' if no such attachment can be found. If
there exists any path component in the given
argument, then an exact match of the path which
has been used to create the attachment is used
directly, but if only the basename of that path
matches then all attachments are traversed to
find an exact match first, and the removal
occurs afterwards; if multiple basenames match,
a `506' error occurs. Message attachments are
treated as absolute pathnames.
If no path component exists in the given argu-
ment, then all attachments will be searched for
`filename=' parameter matches as well as for
matches of the basename of the path which has
been used when the attachment has been created;
multiple matches result in a `506'.
remove-at This will interpret the third argument as a num-
ber and remove the attachment at that list posi-
tion (counting from one!), reporting `210' upon
success or `505' if the argument is not a number
or `501' if no such attachment exists.
header This command allows listing, inspection, and editing of
message headers. Header name case is not normalized, so
that case-insensitive comparison should be used when
matching names. The second argument specifies the subcom-
mand to apply, one of:
insert Create a new or an additional instance of the
header given in the third argument, with the
header body content as given in the fourth
token. It may return `501' if the third argu-
ment specifies a free-form header field name
that is invalid, or if body content extraction
fails to succeed, `505' if any extracted address
does not pass syntax and/or security checks or
on S-nail namespace violations, and `506' to
indicate prevention of excessing a single-
instance header -- note that `Subject:' can be
appended to (a space separator will be added
automatically first). `To:', `Cc:' and `Bcc:'
support the `?single' modifier to enforce treat-
ment as a single addressee, for example `header
insert To?single: 'exa, <m@ple>''; the word
`single' is optional.
`210' is returned upon success, followed by the
name of the header and the list position of the
newly inserted instance. The list position is
always 1 for single-instance header fields. All
free-form header fields are managed in a single
list; also see customhdr.
list Without a third argument a list of all yet
existing headers is given via `210'; this com-
mand is the default command of header if no sec-
ond argument has been given. A third argument
restricts output to the given header only, which
may fail with `501' if no such field is defined.
remove This will remove all instances of the header
given as the third argument, reporting `210'
upon success, `501' if no such header can be
found, and `505' on S-nail namespace violations.
remove-at This will remove from the header given as the
third argument the instance at the list position
(counting from one!) given with the fourth argu-
ment, reporting `210' upon success or `505' if
the list position argument is not a number or on
S-nail namespace violations, and `501' if no
such header instance exists.
show Shows the content of the header given as the
third argument. Dependent on the header type
this may respond with `211' or `212'; any fail-
ure results in `501'.
In compose-mode read-only access to optional pseudo head-
ers in the S-nail private namespace is available:
`Mailx-Command:'
The name of the command that generates the message,
one of `forward', `Lreply', `mail', `Reply',
`reply', `resend'. This pseudo header always exists
(in compose-mode).
`Mailx-Raw-To:'
`Mailx-Raw-Cc:'
`Mailx-Raw-Bcc:'
Represent the frozen initial state of these headers
before any transformation (alias, alternates,
recipients-in-cc etc.) took place.
`Mailx-Orig-Sender:'
`Mailx-Orig-From:'
`Mailx-Orig-To:'
`Mailx-Orig-Cc:'
`Mailx-Orig-Bcc:'
The values of said headers of the original message
which has been addressed by any of reply, forward,
resend. The sender field is special as it is filled
in with the sole sender according to RFC 5322 rules,
it may thus be equal to the from field.
help, ? Show an abstract of the above commands via `211'.
version This command will print the protocol version via `210'.
~A The same as `~i Sign'.
~a The same as `~i sign'.
~b name ...
Add the given names to the list of blind carbon copy recipients.
~c name ...
Add the given names to the list of carbon copy recipients.
~d Read the file specified by the DEAD variable into the message.
~e Invoke the text EDITOR on the message collected so far, then return
to compose mode. ~v can be used for a more display oriented edi-
tor, and ~|| offers a pipe-based editing approach.
~F messages
Read the named messages into the message being sent, including all
message headers and MIME parts, and honouring forward-add-cc as
well as forward-inject-head and forward-inject-tail. If no mes-
sages are specified, read in the current message, the ``dot''.
~f messages
Read the named messages into the message being sent. If no mes-
sages are specified, read in the current message, the ``dot''.
Strips down the list of header fields according to the `forward'
(with posix: `type') white- and blacklist selection of headerpick,
and honours forward-add-cc as well as forward-inject-head and
forward-inject-tail. For MIME multipart messages, only the first
displayable part is included.
~H In interactive mode, edit the message header fields `From:',
`Reply-To:' and `Sender:' by typing each one in turn and allowing
the user to edit the field. The default values for these fields
originate from the from, reply-to and sender variables. In non-
interactive mode this sets ^ERR-NOTTY.
~h In interactive mode, edit the message header fields `To:', `Cc:',
`Bcc:' and `Subject:' by typing each one in turn and allowing the
user to edit the field. In non-interactive mode this sets
^ERR-NOTTY.
~I variable
Insert the value of the specified variable into the message. The
message remains unaltered if the variable is unset or empty. Any
embedded character sequences `\t' horizontal tabulator and `\n'
line feed are expanded in posix mode; otherwise the expansion
should occur at set time ([v15 behaviour may differ] by using the
command modifier wysh).
~i variable
Like ~I, but appends a newline character.
~M messages
Read the named messages into the message being sent, indented by
indentprefix. If no messages are specified, read the current mes-
sage, the ``dot''. Honours forward-add-cc as well as
forward-inject-head and forward-inject-tail.
~m messages
Read the named messages into the message being sent, indented by
indentprefix. If no messages are specified, read the current mes-
sage, the ``dot''. Strips down the list of header fields according
to the `type' white- and blacklist selection of headerpick. Hon-
ours forward-add-cc as well as forward-inject-head and
forward-inject-tail. For MIME multipart messages, only the first
displayable part is included.
~p Display the message collected so far, prefaced by the message
header fields and followed by the attachment list, if any.
~Q Read in the given / current message(s) using the algorithm of quote
(except that is implicitly assumed, even if not set), honouring
quote-add-cc.
~q Abort the message being sent, copying it to the file specified by
the DEAD variable if save is set.
~R filename
Identical to ~r, but indent each line that has been read by
indentprefix.
~r filename [HERE-delimiter]
Read the named file, object to Filename transformations excluding
shell globs and variable expansions, into the message; if filename
is the hyphen-minus `-' then standard input is used (for pasting,
for example). Only in this latter mode HERE-delimiter may be
given: if it is data will be read in until the given HERE-delimiter
is seen on a line by itself, and encountering EOF is an error; the
HERE-delimiter is a required argument in non-interactive mode; if
it is single-quote quoted then the pasted content will not be
expanded, [v15 behaviour may differ] otherwise a future version of
S-nail may perform shell-style expansion on the content.
~s string
Cause the named string to become the current subject field. New-
line (NL) and carriage-return (CR) bytes are invalid and will be
normalized to space (SP) characters.
~t name ...
Add the given name(s) to the direct recipient list.
~U messages
Read in the given / current message(s) excluding all headers,
indented by indentprefix. Honours forward-add-cc as well as
forward-inject-head and forward-inject-tail.
~u messages
Read in the given / current message(s), excluding all headers.
Honours forward-add-cc as well as forward-inject-head and
forward-inject-tail.
~v Invoke the VISUAL editor on the message collected so far, then
return to compose mode. ~e can be used for a less display oriented
editor, and ~|| offers a pipe-based editing approach.
~w filename
Write the message onto the named file, which is object to the usual
Filename transformations. If the file exists, the message is
appended to it.
~x Same as ~q, except that the message is not saved at all.
INTERNAL VARIABLES
Internal S-nail variables are controlled via the set and unset commands;
prefixing a variable name with the string `no' and calling set has the
same effect as using unset: `unset crt' and `set nocrt' do the same
thing. varshow will give more insight on the given variable(s), and set,
when called without arguments, will show a listing of all variables.
Both commands support a more verbose listing mode. Some well-known vari-
ables will also become inherited from the program ENVIRONMENT implicitly,
others can be imported explicitly with the command environ and henceforth
share said properties.
Two different kinds of internal variables exist, and both of which can
also form chains. There are boolean variables, which can only be in one
of the two states ``set'' and ``unset'', and value variables with a(n
optional) string value. For the latter proper quoting is necessary upon
assignment time, the introduction of the section COMMANDS documents the
supported quoting rules.
? wysh set one=val\ 1 two="val 2" \
three='val "3"' four=$'val \'4\''; \
varshow one two three four; \
unset one two three four
Dependent upon the actual option string values may become interpreted as
colour names, command specifications, normal text, etc. They may be
treated as numbers, in which case decimal values are expected if so docu-
mented, but otherwise any numeric format and base that is valid and
understood by the vexpr command may be used, too.
There also exists a special kind of string value, the ``boolean string'',
which must either be a decimal integer (in which case `0' is false and
`1' and any other value is true) or any of the (case-insensitive) strings
`off', `no', `n' and `false' for a false boolean and `on', `yes', `y' and
`true' for a true boolean; a special kind of boolean string is the
``quadoption'': it can optionally be prefixed with the (case-insensitive)
term `ask-', as in `ask-yes'; in interactive mode the user will be
prompted, otherwise the actual boolean is used.
Variable chains extend a plain `variable' with `variable-HOST' and
`variable-USER@HOST' variants. Here `HOST' will be converted to all low-
ercase when looked up (but not when the variable is set or unset!),
[Option]ally IDNA converted, and indeed means `server:port' if a `port'
had been specified in the contextual Uniform Resource Locator URL, see On
URL syntax and credential lookup. Even though this mechanism is based on
URLs no URL percent encoding may be applied to neither of `USER' nor
`HOST', variable chains need to be specified using raw data; the men-
tioned section contains examples. Variables which support chains are
explicitly documented as such, and S-nail treats the base name of any
such variable special, meaning that users should not create custom names
like `variable-xyz' in order to avoid false classifications and treatment
of such variables.
Initial settings
The standard POSIX 2008/Cor 2-2016 mandates the following initial vari-
able settings: noallnet, noappend, asksub, noaskbcc, noautoprint, nobang,
nocmd, nocrt, nodebug, nodot, escape set to `~', noflipr, nofolder,
header, nohold, noignore, noignoreeof, nokeep, nokeepsave, nometoo,
nooutfolder, nopage, prompt set to `? ', noquiet, norecord, save,
nosendwait, noshowto, noSign, nosign, toplines set to `5'.
However, S-nail has built-in some initial (and some default) settings
which (may) diverge, others may become adjusted by one of the Resource
files. Displaying the former is accomplished via set: `$ s-nail -:/ -v
-Xset -Xx'. In general this implementation sets (and has extended the
meaning of) sendwait, and does not support the noonehop variable - use
command line options or mta-arguments to pass options through to a mta.
The default global resource file sets, among others, the variables hold,
keep and keepsave, establishes a default headerpick selection etc., and
should thus be taken into account.
Variables
? (Read-only) The exit status of the last command, or the return
value of the macro called last. This status has a meaning in the
state machine: in conjunction with errexit any non-0 exit status
will cause a program exit, and in posix mode any error while load-
ing (any of the) resource files will have the same effect. ignerr,
one of the Command modifiers, can be used to instruct the state
machine to ignore errors.
! (Read-only) The current error number (errno(3)), which is set after
an error occurred; it is also available via ^ERR, and the error
name and documentation string can be queried via ^ERRNAME and
^ERRDOC. [v15 behaviour may differ] This machinery is new and the
error number is only really usable if a command explicitly states
that it manages the variable !, for others errno will be used in
case of errors, or ^ERR-INVAL if that is 0: it thus may or may not
reflect the real error. The error number may be set with the com-
mand return.
^ (Read-only) This is a multiplexer variable which performs dynamic
expansion of the requested state or condition, of which there are:
^ERR, ^ERRDOC, ^ERRNAME
The number, documentation, and name of the current errno(3),
respectively, which is usually set after an error occurred.
The documentation is an [Option], the name is used if not
available. [v15 behaviour may differ] This machinery is new
and is usually reliable only if a command explicitly states
that it manages the variable !, which is effectively identi-
cal to ^ERR. Each of those variables can be suffixed with a
hyphen minus followed by a name or number, in which case the
expansion refers to the given error. Note this is a direct
mapping of (a subset of) the system error values:
define work {
eval echo \$1: \$^ERR-$1:\
\$^ERRNAME-$1: \$^ERRDOC-$1
vput vexpr i + "$1" 1
if [ $i -lt 16 ]
\xcall work $i
end
}
call work 0
^ERRQUEUE-COUNT, ^ERRQUEUE-EXISTS
The number of messages in the [Option]al queue of errors, and
a string indicating queue state: empty or (translated)
``ERROR''. Always 0 and the empty string, respectively,
unless features includes `,+errors,'.
* (Read-only) Expands all positional parameters (see 1), separated by
the first character of the value of ifs. [v15 behaviour may dif-
fer] The special semantics of the equally named special parameter
of the sh(1) are not yet supported.
@ (Read-only) Expands all positional parameters (see 1), separated by
a space character. If placed in double quotation marks, each posi-
tional parameter is properly quoted to expand to a single parameter
again.
# (Read-only) Expands to the number of positional parameters, i.e.,
the size of the positional parameter stack in decimal.
0 (Read-only) Inside the scope of a defined and called macro this
expands to the name of the calling macro, or to the empty string if
the macro is running from top-level. For the [Option]al regular
expression search and replace operator of vexpr this expands to the
entire matching expression. It represents the program name in
global context.
1 (Read-only) Access of the positional parameter stack. All further
parameters can be accessed with this syntax, too, `2', `3' etc.;
positional parameters can be shifted off the stack by calling
shift. The parameter stack contains, for example, the arguments of
a called defined macro, the matching groups of the [Option]al regu-
lar expression search and replace expression of vexpr, and can be
explicitly created or overwritten with the command vpospar.
account
(Read-only) Is set to the active account.
add-file-recipients
(Boolean) When file or pipe recipients have been specified, mention
them in the corresponding address fields of the message instead of
silently stripping them from their recipient list. By default such
addressees are not mentioned.
allnet
(Boolean) Causes only the local part to be evaluated when comparing
addresses.
append
(Boolean) Causes messages saved in the secondary mailbox MBOX to be
appended to the end rather than prepended. This should always be
set.
askatend
(Boolean) Causes the prompts for `Cc:' and `Bcc:' lists to appear
after the message has been edited.
askattach
(Boolean) If set, S-nail asks an interactive user for files to
attach at the end of each message; An empty line finalizes the
list.
askcc
(Boolean) Causes the interactive user to be prompted for carbon
copy recipients (at the end of each message if askatend or
bsdcompat are set).
askbcc
(Boolean) Causes the interactive user to be prompted for blind car-
bon copy recipients (at the end of each message if askatend or
bsdcompat are set).
asksend
(Boolean) Causes the interactive user to be prompted for confirma-
tion to send the message or reenter compose mode after having been
shown a preliminary envelope summary.
asksign
(Boolean)[Option] Causes the interactive user to be prompted if the
message is to be signed at the end of each message. The smime-sign
variable is ignored when this variable is set.
asksub
(Boolean) Causes S-nail to prompt the interactive user for the sub-
ject upon entering compose mode unless a subject already exists.
attrlist
A sequence of characters to display in the `attribute' column of
the headline as shown in the display of headers; each for one type
of messages (see Message states), with the default being
`NUROSPMFAT+-$~' or `NU *HMFAT+-$~' if the bsdflags variable is
set, in the following order:
`N' new.
`U' unread but old.
`R' new but read.
`O' read and old.
`S' saved.
`P' preserved.
`M' mboxed.
`F' flagged.
`A' answered.
`T' draft.
`+' [v15 behaviour may differ] start of a (collapsed) thread in
threaded mode (see autosort, thread);
`-' [v15 behaviour may differ] an uncollapsed thread in threaded
mode; only used in conjunction with -L.
`$' classified as spam.
`~' classified as possible spam.
autobcc
Specifies a list of recipients to which a blind carbon copy of each
outgoing message will be sent automatically.
autocc
Specifies a list of recipients to which a carbon copy of each out-
going message will be sent automatically.
autocollapse
(Boolean) Causes threads to be collapsed automatically when .Ql
thread Ns ed sort mode is entered (see the collapse command).
autoprint
(Boolean) Enable automatic typeing of a(n existing) ``successive''
message after delete and undelete commands: the message that
becomes the new ``dot'' is shown automatically, as via dp or dt.
autosort
Causes sorted mode (see the sort command) to be entered automati-
cally with the value of this variable as sorting method when a
folder is opened, for example `set autosort=thread'.
bang (Boolean) Enables the substitution of all not (reverse-solidus)
escaped exclamation mark `!' characters by the contents of the last
executed command for the ! shell escape command and ~!, one of the
compose mode COMMAND ESCAPES. If this variable is not set no
reverse solidus stripping is performed.
bind-timeout
[Obsolete] Predecessor of bind-inter-byte-timeout. [v15 behaviour
may differ] Setting this automatically sets the successor.
bind-inter-byte-timeout
[Option] Terminals may generate multi-byte sequences for special
function keys, for example, but these sequences may not become read
as a unit. And multi-byte sequences can be defined freely via
bind. This variable specifies the timeout in milliseconds that the
MLE (see On terminal control and line editor) waits for more bytes
to arrive unless it considers a sequence ``complete''. The default
is 200, the maximum is about 10 seconds. In the following example
the comments state which sequences are affected by this timeout:
? bind base abc echo 0 # abc
? bind base ab,c echo 1 # ab
? bind base abc,d echo 2 # abc
? bind base ac,d echo 3 # ac
? bind base a,b,c echo 4
? bind base a,b,c,d echo 5
? bind base a,b,cc,dd echo 6 # cc and dd
bind-inter-key-timeout
[Option] Multi-key bind sequences do not time out by default. If
this variable is set, then the current key sequence is forcefully
terminated once the timeout (in milliseconds) triggers. The value
should be (maybe significantly) larger than
bind-inter-byte-timeout, but may not excess the maximum, too.
bsdcompat
(Boolean) Sets some cosmetical features to traditional BSD style;
has the same affect as setting askatend and all other variables
prefixed with `bsd'; it also changes the behaviour of emptystart
(which does not exist in BSD).
bsdflags
(Boolean) Changes the letters shown in the first column of a header
summary to traditional BSD style.
bsdheadline
(Boolean) Changes the display of columns in a header summary to
traditional BSD style.
bsdmsgs
(Boolean) Changes some informational messages to traditional BSD
style.
bsdorder
(Boolean) Causes the `Subject:' field to appear immediately after
the `To:' field in message headers and with the ~h COMMAND ESCAPES.
build-cc, build-ld, build-os, build-rest
(Read-only) The build environment, including the compiler, the
linker, the operating system S-nail has been build for, usually
taken from uname(1) via `uname -s', and then lowercased, as well as
all the possibly interesting rest of the configuration and build
environment. This information is also available in the verbose
output of the command version.
charset-7bit
The value that should appear in the `charset=' parameter of
`Content-Type:' MIME header fields when no character set conversion
of the message data was performed. This defaults to US-ASCII, and
the chosen character set should be US-ASCII compatible.
charset-8bit
[Option] The default 8-bit character set that is used as an
implicit last member of the variable sendcharsets. This defaults
to UTF-8 if character set conversion capabilities are available,
and to ISO-8859-1 otherwise (unless the operating system environ-
ment is known to always and exclusively support UTF-8 locales), in
which case the only supported character set is ttycharset and this
variable is effectively ignored.
charset-unknown-8bit
[Option] RFC 1428 specifies conditions when internet mail gateways
shall ``upgrade'' the content of a mail message by using a charac-
ter set with the name `unknown-8bit'. Because of the unclassified
nature of this character set S-nail will not be capable to convert
this character set to any other character set. If this variable is
set any message part which uses the character set `unknown-8bit' is
assumed to really be in the character set given in the value, oth-
erwise the (final) value of charset-8bit is used for this purpose.
This variable will also be taken into account if a MIME type (see
The mime.types files) of a MIME message part that uses the `binary'
character set is forcefully treated as text.
cmd The default value for the pipe command.
colour-disable
(Boolean)[Option] Forcefully disable usage of colours. Also see
the section Coloured display.
colour-pager
(Boolean)[Option] Whether colour shall be used for output that is
paged through PAGER. Note that pagers may need special command
line options, for example less(1) requires the option -R and lv(1)
the option -c in order to support colours. Often doing manual
adjustments is unnecessary since S-nail may perform adjustments
dependent on the value of the environment variable PAGER (see there
for more).
contact-mail, contact-web
(Read-only) Addresses for contact per email and web, respectively,
for bug reports, suggestions, or anything else regarding S-nail.
The former can be used directly: `? eval mail $contact-mail'.
content-description-forwarded-message,
content-description-quote-attachment,
content-description-smime-message,
content-description-smime-signature
[Option](partially) Strings which will be placed in according
`Content-Description:' headers if non-empty. They all have default
values, for example `Forwarded message'.
crt In a(n interactive) terminal session, then if this valued variable
is set it will be used as a threshold to determine how many lines
the given output has to span before it will be displayed via the
configured PAGER; Usage of the PAGER can be forced by setting this
to the value `0', setting it without a value will deduce the cur-
rent height of the terminal screen to compute the threshold (see
LINES, screen and stty(1)). [v15 behaviour may differ] At the
moment this uses the count of lines of the message in wire format,
which, dependent on the mime-encoding of the message, is unrelated
to the number of display lines. (The software is old and histori-
cally the relation was a given thing.)
customhdr
Define a set of custom headers to be injected into newly composed
or forwarded messages. A custom header consists of the field name
followed by a colon `:' and the field content body. Standard
header field names cannot be overwritten by a custom header, with
the exception of `Comments:' and `Keywords:'. Different to the
command line option -C the variable value is interpreted as a
comma-separated list of custom headers: to include commas in header
bodies they need to become escaped with reverse solidus `\'. Head-
ers can be managed more freely in Compose mode via ~^.
? set customhdr='Hdr1: Body1-1\, Body1-2, Hdr2: Body2'
datefield
Controls the appearance of the `%d' date and time format specifica-
tion of the headline variable, that is used, for example, when
viewing the summary of headers. If unset, then the local receiving
date is used and displayed unformatted, otherwise the message send-
ing `Date:'. It is possible to assign a strftime(3) format string
and control formatting, but embedding newlines via the `%n' format
is not supported, and will result in display errors. The default
is `%Y-%m-%d %H:%M', and also see datefield-markout-older.
datefield-markout-older
Only used in conjunction with datefield. Can be used to create a
visible distinction of messages dated more than a day in the
future, or older than six months, a concept comparable to the -l
option of the POSIX utility ls(1). If set to the empty string,
then the plain month, day and year of the `Date:' will be dis-
played, but a strftime(3) format string to control formatting can
be assigned. The default is `%Y-%m-%d'.
debug
(Boolean) (Almost) Enter a debug-only sandbox mode which generates
many log messages, disables the actual delivery of messages, and
also implies norecord as well as nosave. Also see verbose.
disposition-notification-send
(Boolean)[Option] Emit a `Disposition-Notification-To:' header (RFC
3798) with the message. This requires the from variable to be set.
dot (Boolean) When dot is set, a period `.' on a line by itself during
message input in (interactive or batch -#) Compose mode will be
treated as end-of-message (in addition to the normal end-of-file
condition). This behaviour is implied in posix mode with a set
ignoreeof.
dotlock-disable
(Boolean)[Option] Disable creation of dotlock files for MBOX data-
bases.
dotlock-ignore-error
[Obsolete](Boolean)[Option] Ignore failures when creating dotlock
files. Please use dotlock-disable instead.
editalong
If this variable is set then the editor is started automatically
when a message is composed in interactive mode. If the value
starts with the letter `v' then this acts as if ~v, otherwise as if
~e (see COMMAND ESCAPES) had been specified. The editheaders vari-
able is implied for this automatically spawned editor session.
editheaders
(Boolean) When a message is edited while being composed, its header
is included in the editable text.
emptystart
(Boolean) When entering interactive mode S-nail normally writes
``No mail for user'' and exits immediately if a mailbox is empty or
does not exist. If this variable is set S-nail starts even with an
empty or non-existent mailbox (the latter behaviour furtherly
depends upon bsdcompat, though).
errexit
(Boolean) Let each command with a non-0 exit status, including
every called macro which returns a non-0 status, cause a program
exit unless prefixed by ignerr (see Command modifiers). This also
affects COMMAND ESCAPES, but which use a different modifier for
ignoring the error. Please refer to the variable ? for more on
this topic.
errors-limit
[Option] Maximum number of entries in the errors queue.
escape
The first character of this value defines the escape character for
COMMAND ESCAPES in Compose mode. The default value is the charac-
ter tilde `~'. If set to the empty string, command escapes are
disabled.
expandaddr
If unset only user name and email address recipients are allowed On
sending mail, and non-interactive mode. If set without value all
possible recipient types will be accepted. A value is parsed as a
comma-separated list of case-insensitive strings, and if that con-
tains `restrict' behaviour equals the former except when in inter-
active mode or if COMMAND ESCAPES were enabled via -~ or -#, in
which case it equals the latter, allowing all address types.
`restrict' really acts like `restrict,-all,+name,+addr', so care
for ordering issues must be taken.
Recipient types can be added and removed with a plus sign `+' or
hyphen-minus `-' prefix, respectively. By default invalid or dis-
allowed types are filtered out and cause a warning, hard send
errors need to be enforced by including `fail'. The value `all'
covers all types, `fcc' whitelists `Fcc:' header targets regardless
of other settings, `file' file targets (it includes `fcc'), `pipe'
command pipeline targets, `name' user names still unexpanded after
alias and mta-aliases processing and thus left for expansion by the
mta (invalid for the built-in SMTP one), and `addr' network
addresses. Targets are interpreted in the given order, so that
`restrict,fail,+file,-all,+addr' will cause hard errors for any
non-network address recipient address unless running interactively
or having been started with the option -~ or -#; in the latter
case(s) any type may be used.
User name receivers addressing valid local users can be expanded to
fully qualified network addresses (also see hostname) by including
`nametoaddr' in the list. Historically invalid recipients were
stripped off without causing errors, this can be changed by making
`failinvaddr' an entry of the list (it really acts like
`failinvaddr,+addr'). Likewise, `domaincheck' (really
`domaincheck,+addr') compares address domain names against a
whitelist and strips off (`fail' for hard errors) addressees which
fail this test; the domain name `localhost' and the non-empty value
of hostname (the real hostname otherwise) are always whitelisted,
expandaddr-domaincheck can be set to extend this list. Finally
some address providers (for example -b, -c and all other command
line recipients) will be evaluated as if specified within dollar-
single-quotes (see Shell-style argument quoting) if the value list
contains the string `shquote'.
expandaddr-domaincheck
Can be set to a comma-separated list of domain names which should
be whitelisted for the evaluation of the `domaincheck' mode of
expandaddr. IDNA encoding is not automatically performed,
addrcodec can be used to prepare the domain (of an address).
expandargv
Unless this variable is set additional mta (Mail-Transfer-Agent)
arguments from the command line, as can be given after a -- separa-
tor, results in a program termination with failure status. The
same can be accomplished by using the special (case-insensitive)
value `fail'. A lesser strict variant is the otherwise identical
`restrict', which does accept such arguments in interactive mode,
or if tilde commands were enabled explicitly by using one of the
command line options -~ or -#. The empty value will allow uncondi-
tional usage.
features
(Read-only) String giving a list of optional features. Features
are preceded with a plus sign `+' if they are available, with a
hyphen-minus `-' otherwise. To ease substring matching the string
starts and ends with a comma. The output of the command version
includes this information in a more pleasant output.
flipr
(Boolean) This setting reverses the meanings of a set of reply com-
mands, turning the lowercase variants, which by default address all
recipients included in the header of a message (reply, respond,
followup) into the uppercase variants, which by default address the
sender only (Reply, Respond, Followup) and vice versa.
folder
The default path under which mailboxes are to be saved: filenames
that begin with the plus sign `+' will have the plus sign replaced
with the value of this variable if set, otherwise the plus sign
will remain unchanged when doing Filename transformations; also see
folder for more on this topic, and know about standard imposed
implications of outfolder. The value supports a subset of trans-
formations itself, and if the non-empty value does not start with a
solidus `/', then the value of HOME will be prefixed automatically.
Once the actual value is evaluated first, the internal variable
folder-resolved will be updated for caching purposes.
folder-hook-FOLDER, folder-hook
Names a defined macro which will be called whenever a folder is
opened. The macro will also be invoked when new mail arrives, but
message lists for commands executed from the macro only include
newly arrived messages then. localopts are activated by default in
a folder hook, causing the covered settings to be reverted once the
folder is left again.
The specialized form will override the generic one if `FOLDER'
matches the file that is opened. Unlike other folder specifica-
tions, the fully expanded name of a folder, without metacharacters,
is used to avoid ambiguities. However, if the mailbox resides
under folder then the usual `+' specification is tried in addition,
so that if folder is ``mail'' (and thus relative to the user's home
directory) then /home/usr1/mail/sent will be tried as
`folder-hook-/home/usr1/mail/sent' first, but then followed by
`folder-hook-+sent'.
folder-resolved
(Read-only) Set to the fully resolved path of folder once that
evaluation has occurred; rather internal.
followup-to
(Boolean) Controls whether a `Mail-Followup-To:' header is gener-
ated when sending messages to known mailing lists. The user as
determined via from (or, if that contains multiple addresses,
sender) will be placed in there if any list addressee is not a sub-
scribed list. Also see followup-to-honour and the commands mlist,
mlsubscribe, reply and Lreply.
followup-to-add-cc
(Boolean) Controls whether the user will be added to the messages'
`Cc:' list in addition to placing an entry in `Mail-Followup-To:'
(see followup-to).
followup-to-honour
Controls whether a `Mail-Followup-To:' header is honoured when
group-replying to a message via reply or Lreply. This is a
quadoption; if set without a value it defaults to ``yes'', and see
followup-to.
forward-add-cc
(Boolean) Whether senders of messages forwarded via ~F, ~f, ~m, ~U
or ~u shall be made members of the carbon copies `Cc:' list.
forward-as-attachment
(Boolean) Original messages are normally sent as inline text with
the forward command, and only the first part of a multipart message
is included. With this setting enabled messages are sent as unmod-
ified MIME `message/rfc822' attachments with all of their parts
included.
forward-inject-head, forward-inject-tail
The strings to put before and after the text of a message with the
forward command, respectively. The former defaults to `--------
Original Message --------\n'. Special format directives in these
strings will be expanded if possible, and if so configured the out-
put will be folded according to quote-fold; for more please refer
to quote-inject-head. Injections will not be performed by forward
if the variable forward-as-attachment is set -- the COMMAND ESCAPES
~F, ~f, ~M, ~m, ~U, ~u always inject.
from The address (or a list of addresses) to put into the `From:' field
of the message header, quoting RFC 5322: the author(s) of the mes-
sage, that is, the mailbox(es) of the person(s) or system(s)
responsible for the writing of the message. According to that RFC
setting the sender variable is required if from contains more than
one address. [v15 behaviour may differ] Please expect automatic
management of the from and sender relationship. Dependent on the
context these addresses are handled as if they were in the list of
alternates.
If a file-based MTA is used, then from (or, if that contains multi-
ple addresses, sender) can nonetheless be used as the envelope
sender address at the MTA protocol level (the RFC 5321 reverse-
path), either via the -r command line option (without argument; see
there for more), or by setting r-option-implicit.
If the machine's hostname is not valid at the Internet (for example
at a dialup machine), then either this variable or hostname
([v15-compat] a SMTP-based mta adds even more fine-tuning capabili-
ties with smtp-hostname) have to be set: if so the message and MIME
part related unique ID fields `Message-ID:' and `Content-ID:' will
be created (except when disallowed by message-id-disable or
stealthmua).
fullnames
(Boolean) Due to historical reasons comments and name parts of
email addresses are removed by default when sending mail, replying
to or forwarding a message. If this variable is set such stripping
is not performed.
fwdheading
[Obsolete] Predecessor of forward-inject-head.
header
(Boolean) Causes the header summary to be written at startup and
after commands that affect the number of messages or the order of
messages in the current folder. Unless in posix mode a header sum-
mary will also be displayed on folder changes. The command line
option -N can be used to set noheader.
headline
A format string to use for the summary of headers. Format speci-
fiers in the given string start with a percent sign `%' and may be
followed by an optional decimal number indicating the field width
-- if that is negative, the field is to be left-aligned. Names and
addresses are subject to modifications according to showname and
showto. Valid format specifiers are:
`%%' A plain percent sign.
`%>' ``Dotmark'': a space character but for the current message
(``dot''), for which it expands to `>' (dependent on
headline-plain).
`%<' ``Dotmark'': a space character but for the current message
(``dot''), for which it expands to `<' (dependent on
headline-plain).
`%$' [Option] The spam score of the message, as has been classi-
fied via the command spamrate. Shows only a replacement
character if there is no spam support.
`%a' Message attribute character (status flag); the actual con-
tent can be adjusted by setting attrlist.
`%d' The date found in the `Date:' header of the message when
datefield is set (the default), otherwise the date when the
message was received. Formatting can be controlled by
assigning a strftime(3) format string to datefield (and
datefield-markout-older).
`%e' The indenting level in `thread'ed sort mode.
`%f' The address of the message sender.
`%i' The message thread tree structure. (Note that this format
does not support a field width, and honours
headline-plain.)
`%L' Mailing list status: is the addressee of the message a
known `l' (mlist) or `L' mlsubscribed mailing list? The
letter `P' announces the presence of a RFC 2369
`List-Post:' header, which makes a message a valuable tar-
get of Lreply.
`%l' The number of lines of the message, if available.
`%m' Message number.
`%o' The number of octets (bytes) in the message, if available.
`%S' Message subject (if any) in double quotes.
`%s' Message subject (if any).
`%t' The position in threaded/sorted order.
`%U' The value 0 except in an IMAP mailbox, where it expands to
the UID of the message.
The default is `%>%a%m %-18f %16d %4l/%-5o %i%-s', or
`%>%a%m %20-f %16d %3l/%-5o %i%-S' if bsdcompat is set. Also see
attrlist, headline-plain and headline-bidi.
headline-bidi
Bidirectional text requires special treatment when displaying head-
ers, because numbers (in dates or for file sizes etc.) will not
affect the current text direction, in effect resulting in ugly line
layouts when arabic or other right-to-left text is to be displayed.
On the other hand only a minority of terminals is capable to cor-
rectly handle direction changes, so that user interaction is neces-
sary for acceptable results. Note that extended host system sup-
port is required nonetheless, e.g., detection of the terminal char-
acter set is one precondition; and this feature only works in an
Unicode (i.e., UTF-8) locale.
In general setting this variable will cause S-nail to encapsulate
text fields that may occur when displaying headline (and some other
fields, like dynamic expansions in prompt) with special Unicode
control sequences; it is possible to fine-tune the terminal support
level by assigning a value: no value (or any value other than `1',
`2' and `3') will make S-nail assume that the terminal is capable
to properly deal with Unicode version 6.3, in which case text is
embedded in a pair of U+2068 (FIRST STRONG ISOLATE) and U+2069 (POP
DIRECTIONAL ISOLATE) characters. In addition no space on the line
is reserved for these characters.
Weaker support is chosen by using the value `1' (Unicode 6.3, but
reserve the room of two spaces for writing the control sequences
onto the line). The values `2' and `3' select Unicode 1.1 support
(U+200E, LEFT-TO-RIGHT MARK); the latter again reserves room for
two spaces in addition.
headline-plain
(Boolean) On Unicode (UTF-8) aware terminals enhanced graphical
symbols are used by default for certain entries of headline. If
this variable is set only basic US-ASCII symbols will be used.
history-file
[Option] The (expandable) location of a permanent history file for
the MLE line editor (On terminal control and line editor). Also
see history-size.
history-gabby
[Option] Add more entries to the MLE history as is normally done.
A comma-separated list of case-insensitive strings can be used to
fine-tune which gabby entries shall be allowed. If it contains
`errors', erroneous commands will also be added. `all' adds all
optional entries, and is the fallback chattiness identifier of
on-history-addition.
history-gabby-persist
(Boolean)[Option] The history-gabby entries will not be saved in
persistent storage unless this variable is set. The knowledge of
whether a persistent entry was gabby is not lost. Also see
history-file.
history-size
[Option] Setting this variable imposes a limit on the number of
concurrent history entries. If set to the value 0 then no further
history entries will be added, and loading and incorporation of the
history-file upon program startup can also be suppressed by doing
this. Runtime changes will not be reflected before the history is
saved or loaded (again).
hold (Boolean) This setting controls whether messages are held in the
system inbox, and it is set by default.
hostname
Used instead of the value obtained from uname(3) and getaddrinfo(3)
as the hostname when expanding local addresses, for example in
`From:' (also see On sending mail, and non-interactive mode, for
expansion of addresses that have a valid user-, but no domain name
in angle brackets). If either of from or this variable is set the
message and MIME part related unique ID fields `Message-ID:' and
`Content-ID:' will be created (except when disallowed by
message-id-disable or stealthmua). If the [Option]al IDNA support
is available (see idna-disable) variable assignment is aborted when
a necessary conversion fails.
Setting it to the empty string will cause the normal hostname to be
used, but nonetheless enables creation of said ID fields.
[v15-compat] in conjunction with the built-in SMTP mta
smtp-hostname also influences the results: one should produce some
test messages with the desired combination of hostname, and/or
from, sender etc. first.
idna-disable
(Boolean)[Option] Can be used to turn off the automatic conversion
of domain names according to the rules of IDNA (internationalized
domain names for applications). Since the IDNA code assumes that
domain names are specified with the ttycharset character set, an
UTF-8 locale charset is required to represent all possible interna-
tional domain names (before conversion, that is).
ifs The input field separator that is used ([v15 behaviour may differ]
by some functions) to determine where to split input data.
1. Unsetting is treated as assigning the default value, ` \t\n'.
2. If set to the empty value, no field splitting will be per-
formed.
3. If set to a non-empty value, all whitespace characters are
extracted and assigned to the variable ifs-ws.
a. ifs-ws will be ignored at the beginning and end of input.
Diverging from POSIX shells default whitespace is removed in
addition, which is owed to the entirely different line content
extraction rules.
b. Each occurrence of a character of ifs will cause field-split-
ting, any adjacent ifs-ws characters will be skipped.
ifs-ws
(Read-only) Automatically deduced from the whitespace characters in
ifs.
ignore
(Boolean) Ignore interrupt signals from the terminal while entering
messages; instead echo them as `@' characters and discard the cur-
rent line.
ignoreeof
(Boolean) Ignore end-of-file conditions (`control-D') in Compose
mode on message input and in interactive command input. If set an
interactive command input session can only be left by explicitly
using one of the commands exit and quit, and message input in com-
pose mode can only be terminated by entering a period `.' on a line
by itself or by using the ~. COMMAND ESCAPES; Setting this implies
the behaviour that dot describes in posix mode.
inbox
If this is set to a non-empty string it will specify the user's
primary system mailbox, overriding MAIL and the system-dependent
default, and (thus) be used to replace `%' when doing Filename
transformations; also see folder for more on this topic. The value
supports a subset of transformations itself.
indentprefix
String used by the ~m, ~M and ~R COMMAND ESCAPES and by the quote
option for indenting messages, in place of the POSIX mandated
default tabulator character `\t'. Also see quote-chars.
keep (Boolean) If set, an empty primary system mailbox file is not
removed. Note that, in conjunction with posix mode any empty file
will be removed unless this variable is set. This may improve the
interoperability with other mail user agents when using a common
folder directory, and prevents malicious users from creating fake
mailboxes in a world-writable spool directory. [v15 behaviour may
differ] Only local regular (MBOX) files are covered, Maildir and
other mailbox types will never be removed, even if empty.
keep-content-length
(Boolean) When (editing messages and) writing MBOX mailbox files
S-nail can be told to keep the `Content-Length:' and `Lines:'
header fields that some MUAs generate by setting this variable.
Since S-nail does neither use nor update these non-standardized
header fields (which in itself shows one of their conceptual prob-
lems), stripping them should increase interoperability in between
MUAs that work with with same mailbox files. Note that, if this is
not set but writebackedited, as below, is, a possibly performed
automatic stripping of these header fields already marks the mes-
sage as being modified. [v15 behaviour may differ] At some future
time S-nail will be capable to rewrite and apply an mime-encoding
to modified messages, and then those fields will be stripped
silently.
keepsave
(Boolean) When a message is saved it is usually discarded from the
originating folder when S-nail is quit. This setting causes all
saved message to be retained.
line-editor-cpl-word-breaks
[Option] List of bytes which are used by the mle-complete tabulator
completion to decide where word boundaries exist, by default
`"'@=;|:' [v15 behaviour may differ] This mechanism is yet
restricted.
line-editor-disable
(Boolean) Turn off any line editing capabilities (from S-nails POW,
see On terminal control and line editor for more).
line-editor-no-defaults
(Boolean)[Option] Do not establish any default key binding.
log-prefix
Error log message prefix string (`s-nail: ').
mailbox-display
(Read-only) The name of the current mailbox (folder), possibly
abbreviated for display purposes.
mailbox-resolved
(Read-only) The fully resolved path of the current mailbox.
mailcap-disable
(Boolean)[Option] Turn off consideration of MIME type handlers
from, and implicit loading of The Mailcap files.
mailx-extra-rc
An additional startup file that is loaded as the last of the
Resource files. Use this file for commands that are not understood
by other POSIX mailx(1) implementations, i.e., mostly anything
which is not covered by Initial settings.
markanswered
(Boolean) When a message is replied to and this variable is set, it
is marked as having been answered. See the section Message states.
mbox-fcc-and-pcc
(Boolean) By default all file and pipe message receivers (see
expandaddr) will be fed valid MBOX database entry message data (see
folder, mbox-rfc4155), and existing file targets will become
extended in compliance to RFC 4155. If this variable is unset then
a plain standalone RFC 5322 message will be written, and existing
file targets will be overwritten.
mbox-rfc4155
(Boolean) When opening MBOX mailbox databases, and in order to
achieve compatibility with old software, the very tolerant POSIX
standard rules for detecting message boundaries (so-called `From_'
lines) are used instead of the stricter rules from the standard RFC
4155. This behaviour can be switched by setting this variable.
This may temporarily be handy when S-nail complains about invalid
`From_' lines when opening a MBOX: in this case setting this vari-
able and re-opening the mailbox in question may correct the result.
If so, copying the entire mailbox to some other file, as in `copy *
SOME-FILE', will perform proper, all-compatible `From_' quoting for
all detected messages, resulting in a valid MBOX mailbox. ([v15
behaviour may differ] The better and non-destructive approach is to
re-encode invalid messages, as if it would be created anew, instead
of mangling the `From_' lines; this requires the structural code
changes of the v15 rewrite.) Finally the variable can be unset
again:
define mboxfix {
localopts yes; wysh set mbox-rfc4155;\
wysh File "${1}"; copy * "${2}"
}
call mboxfix /tmp/bad.mbox /tmp/good.mbox
memdebug
(Boolean) Internal development variable. (Keeps memory debug
enabled even if debug is not set.)
message-id-disable
(Boolean) By setting this variable the generation of `Message-ID:'
and `Content-ID:' message and MIME part headers can be completely
suppressed, effectively leaving this task up to the mta (Mail-
Transfer-Agent) or the SMTP server. Note that according to RFC
5321 a SMTP server is not required to add this field by itself, so
it should be ensured that it accepts messages without `Message-ID'.
message-inject-head
A string to put at the beginning of each new message, followed by a
newline. [Obsolete] The escape sequences tabulator `\t' and new-
line `\n' are understood (use the wysh prefix when setting the
variable(s) instead).
message-inject-tail
A string to put at the end of each new message, followed by a new-
line. [Obsolete] The escape sequences tabulator `\t' and newline
`\n' are understood (use the wysh prefix when setting the vari-
able(s) instead). Also see on-compose-leave.
metoo
(Boolean) Usually, when an alias expansion contains the sender, the
sender is removed from the expansion. Setting this option sup-
presses these removals. Note that a set metoo also causes a `-m'
option to be passed through to the mta (Mail-Transfer-Agent);
though most of the modern MTAs no longer document this flag, no MTA
is known which does not support it (for historical compatibility).
mime-allow-text-controls
(Boolean) When sending messages, each part of the message is MIME-
inspected in order to classify the `Content-Type:' and
`Content-Transfer-Encoding:' (see mime-encoding) that is required
to send this part over mail transport, i.e., a computation rather
similar to what the file(1) command produces when used with the
`--mime' option.
This classification however treats text files which are encoded in
UTF-16 (seen for HTML files) and similar character sets as binary
octet-streams, forcefully changing any `text/plain' or `text/html'
specification to `application/octet-stream': If that actually hap-
pens a yet unset charset MIME parameter is set to `binary', effec-
tively making it impossible for the receiving MUA to automatically
interpret the contents of the part.
If this variable is set, and the data was unambiguously identified
as text data at first glance (by a `.txt' or `.html' file exten-
sion), then the original `Content-Type:' will not be overwritten.
mime-alternative-favour-rich
(Boolean) If this variable is set then rich MIME alternative parts
(e.g., HTML) will be preferred in favour of included plain text
versions when displaying messages, provided that a handler exists
which produces output that can be (re)integrated into S-nail's nor-
mal visual display.
mime-counter-evidence
Normally the `Content-Type:' field is used to decide how to handle
MIME parts. Some MUAs, however, do not use The mime.types files
(also see HTML mail and MIME attachments) or a similar mechanism to
correctly classify content, but specify an unspecific MIME type
(`application/octet-stream') even for plain text attachments. If
this variable is set then S-nail will try to re-classify such MIME
message parts, if possible, for example via a possibly existing
attachment filename. A non-empty value may also be given, in which
case a number is expected, actually a carrier of bits, best speci-
fied as a binary value, like `0b1111'.
o If bit two is set (counting from 1, decimal 2) then the
detected mimetype will be carried along with the message and be
used for deciding which MIME handler is to be used, for exam-
ple; when displaying such a MIME part the part-info will indi-
cate the overridden content-type by showing a plus sign `+'.
o If bit three is set (decimal 4) then the counter-evidence is
always produced and a positive result will be used as the MIME
type, even forcefully overriding the parts given MIME type.
o If bit four is set (decimal 8) as a last resort the actual con-
tent of `application/octet-stream' parts will be inspected, so
that data which looks like plain text can be treated as such.
This mode is even more relaxed when data is to be displayed to
the user or used as a message quote (data consumers which man-
gle data for display purposes, which includes masking of con-
trol characters, for example).
mime-encoding
The MIME `Content-Transfer-Encoding' to use in outgoing text mes-
sages and message parts, where applicable (7-bit clean text mes-
sages are without an encoding if possible):
`8bit' (Or `8b'.) 8-bit transport effectively causes the raw data
be passed through unchanged, but may cause problems when
transferring mail messages over channels that are not ESMTP
(RFC 1869) compliant. Also, several input data constructs
are not allowed by the specifications and may cause a dif-
ferent transfer-encoding to be used. By established rules
and popular demand occurrences of `^From_' (see
mbox-rfc4155) will be MBOXO quoted (prefixed with greater-
than sign `>') instead of causing a non-destructive encod-
ing like `quoted-printable' to be chosen, unless context
(like message signing) requires otherwise.
`quoted-printable'
(Or `qp'.) Quoted-printable encoding is 7-bit clean and
has the property that ASCII characters are passed through
unchanged, so that an english message can be read as-is; it
is also acceptable for other single-byte locales that share
many characters with ASCII, for example ISO-8859-1. The
encoding will cause a large overhead for messages in other
character sets: for example it will require up to twelve
(12) bytes to encode a single UTF-8 character of four (4)
bytes. It is the default encoding.
`base64'
(Or `b64'.) This encoding is 7-bit clean and will always
be used for binary data. This encoding has a constant
input:output ratio of 3:4, regardless of the character set
of the input data it will encode three bytes of input to
four bytes of output. This transfer-encoding is not human
readable without performing a decoding step.
mime-force-sendout
(Boolean)[Option] Whenever it is not acceptable to fail sending out
messages because of non-convertible character content this variable
may be set. It will, as a last resort, classify the part content
as `application/octet-stream'. Please refer to the section
Character sets for the complete picture of character set conver-
sion, and HTML mail and MIME attachments for how to internally or
externally handle part content.
mimetypes-load-control
Can be used to control which of The mime.types files are loaded: if
the letter `u' is part of the option value, then the user's per-
sonal ~/.mime.types file will be loaded (if it exists); likewise
the letter `s' controls loading of the system wide /etc/mime.types;
directives found in the user file take precedence, letter matching
is case-insensitive. If this variable is not set S-nail will try
to load both files. Incorporation of the S-nail-built-in MIME
types cannot be suppressed, but they will be matched last (the
order can be listed via mimetype).
More sources can be specified by using a different syntax: if the
value string contains an equals sign `=' then it is instead parsed
as a comma-separated list of the described letters plus
`f=FILENAME' pairs; the given filenames will be expanded and
loaded, and their content may use the extended syntax that is
described in the section The mime.types files. Directives found in
such files always take precedence (are prepended to the MIME type
cache).
mta Select an alternate Mail-Transfer-Agent by either specifying the
full pathname of an executable (a `file://' prefix may be given),
or [Option]ally a SMTP aka SUBMISSION protocol URL [v15-compat]:
submissions://[user[:password]@]server[:port]
([no v15-compat]: `[smtp://]server[:port]'.) The default has been
chosen at compile time. MTA data transfers are always performed in
asynchronous child processes, and without supervision unless either
the sendwait or the verbose variable is set. Also see mta-bcc-ok.
[Option]ally expansion of aliases(5) can be performed by setting
mta-aliases.
For testing purposes there is the `test' pseudo-MTA, which dumps to
standard output or optionally to a file, and honours
mbox-fcc-and-pcc:
$ echo text | s-nail -:/ -Smta=test -s ubject ex AT am.ple
$ </dev/null s-nail -:/ -Smta=test://./xy ex AT am.ple
For a file-based MTA it may be necessary to set mta-argv0 in in
order to choose the right target of a modern mailwrapper(8) envi-
ronment. It will be passed command line arguments from several
possible sources: from the variable mta-arguments if set, from the
command line if given and the variable expandargv allows their use.
Argument processing of the MTA will be terminated with a -- separa-
tor.
The otherwise occurring implicit usage of the following MTA command
line arguments can be disabled by setting the boolean variable
mta-no-default-arguments (which will also disable passing -- to the
MTA): -i (for not treating a line with only a dot `.' character as
the end of input), -m (shall the variable metoo be set) and -v (if
the verbose variable is set); in conjunction with the -r command
line option or r-option-implicit -f as well as possibly -F will
(not) be passed.
[Option]ally S-nail can send mail over SMTP aka SUBMISSION network
connections to a single defined smart host by setting this variable
to a SMTP or SUBMISSION URL (see On URL syntax and credential
lookup). An authentication scheme can be specified via the vari-
able chain smtp-auth. Encrypted network connections are
[Option]ally available, the section Encrypted network communication
should give an overview and provide links to more information on
this. Note that with some mail providers it may be necessary to
set the smtp-hostname variable in order to use a specific combina-
tion of from, hostname and mta. Network communication socket time-
outs are configurable via socket-connect-timeout. All generated
network traffic may be proxied over a SOCKS socks-proxy, it can be
logged by setting verbose twice. The following SMTP variants may
be used:
o The plain SMTP protocol (RFC 5321) that normally lives on the
server port 25 and requires setting the smtp-use-starttls vari-
able to enter a TLS encrypted session state. Assign a value
like [v15-compat] `smtp://[user[:password]@]server[:port]' ([no
v15-compat] `smtp://server[:port]') to choose this protocol.
o The so-called SMTPS which is supposed to live on server port
465 and is automatically TLS secured. Unfortunately it never
became a standardized protocol and may thus not be supported by
your hosts network service database - in fact the port number
has already been reassigned to other protocols!
SMTPS is nonetheless a commonly offered protocol and thus can
be chosen by assigning a value like [v15-compat]
`smtps://[user[:password]@]server[:port]' ([no v15-compat]
`smtps://server[:port]'); due to the mentioned problems it is
usually necessary to explicitly specify the port as `:465',
however.
o The SUBMISSION protocol (RFC 6409) lives on server port 587 and
is identically to the SMTP protocol from S-nail's point of
view; it requires setting smtp-use-starttls to enter a TLS
secured session state; e.g., [v15-compat]
`submission://[user[:password]@]server[:port]'.
o The SUBMISSIONS protocol (RFC 8314) that lives on server port
465 and is TLS secured by default. It can be chosen by assign-
ing a value like [v15-compat]
`submissions://[user[:password]@]server[:port]'. Due to the
problems mentioned for SMTPS above and the fact that SUBMIS-
SIONS is new and a successor that lives on the same port as the
historical engineering mismanagement named SMTPS, it is usually
necessary to explicitly specify the port as `:465'.
mta-aliases
[Option] If set to a path pointing to a text file in valid MTA
(Postfix) aliases(5) format, the file is loaded and cached (manage-
able with mtaaliases), and henceforth plain `name' (see expandaddr)
message receiver names are recursively expanded as a last expansion
step, after the distribution lists which can be created with alias.
Constraints on aliases(5) content support: only local addresses
(names) which are valid usernames (`[a-z_][a-z0-9_-]*[$]?') are
treated as expandable aliases, and [v15 behaviour may differ]
`:include:/file/name' directives are not supported. By including
`-name' in expandaddr it can be asserted that only expanded names
(mail addresses) are passed through to the MTA.
mta-arguments
Arguments to pass through to a file-based mta (Mail-Transfer-
Agent), parsed according to Shell-style argument quoting into an
array of arguments which will be joined onto MTA options from other
sources, for example `? wysh set mta-arguments='-t -X "/tmp/my
log"''.
mta-no-default-arguments
(Boolean) Avoids passing standard command line options to a file-
based mta (please see there).
mta-no-receiver-arguments
(Boolean) By default all receiver addresses will be passed as com-
mand line options to a file-based mta. Setting this variable dis-
ables this behaviour to aid those MTAs which employ special treat-
ment of such arguments. Doing so can make it necessary to pass a
-t via mta-arguments, to testify the MTA that it should use the
passed message as a template.
mta-argv0
Many systems use a so-called mailwrapper(8) environment to ensure
compatibility with sendmail(1). This works by inspecting the name
that was used to invoke the mail delivery system. If this variable
is set then the mailwrapper (the program that is actually executed
when calling the file-based mta) will treat its contents as that
name.
mta-bcc-ok
(Boolean) In violation of RFC 5322 some MTAs do not remove `Bcc:'
header lines from transported messages after having noted the
respective receivers for addressing purposes. (The MTAs Exim and
Courier for example require the command line option -t to enforce
removal.) Unless this is set corresponding receivers are addressed
by protocol-specific means or MTA command line options only, the
header itself is stripped before being sent over the wire.
netrc-lookup-USER@HOST, netrc-lookup-HOST, netrc-lookup
(Boolean)[v15-compat][Option] Used to control usage of the user's
~/.netrc file for lookup of account credentials, as documented in
the section On URL syntax and credential lookup and for the command
netrc; the section The .netrc file documents the file format. Also
see netrc-pipe.
netrc-pipe
[v15-compat][Option] When ~/.netrc is loaded (see netrc and
netrc-lookup) then S-nail will read the output of a shell pipe
instead of the user's ~/.netrc file if this variable is set (to the
desired shell command). This can be used to, for example, store ~/
.netrc in encrypted form: `? set netrc-pipe='gpg -qd
~/.netrc.pgp''.
newfolders
[Option] If this variable has the value `maildir', newly created
local folders will be in Maildir instead of MBOX format.
newmail
Checks for new mail in the current folder each time the prompt is
shown. A Maildir folder must be re-scanned to determine if new
mail has arrived. If this variable is set to the special value
`nopoll' then a Maildir folder will not be rescanned completely,
but only timestamp changes are detected. Maildir folders are
[Option]al.
outfolder
(Boolean) Causes a non-absolute filename specified in record, as
well as the sender-based filenames of the Copy, Save, Followup and
followup commands to be interpreted relative to the folder direc-
tory rather than relative to the current directory.
on-account-cleanup-ACCOUNT, on-account-cleanup
Macro hook which will be called once an account is left, as the
very last step before unrolling per-account localopts. This hook
is run even in case of fatal errors, including those generated by
switching to the account as such, and it is advisable to perform
only absolutely necessary actions, like cleaning up alternates, for
example. The specialized form is used in favour of the generic one
if found.
on-compose-cleanup
Macro hook which will be called after the message has been sent (or
not, in case of failures), as the very last step before unrolling
compose mode localopts. This hook is run even in case of fatal
errors, and it is advisable to perform only absolutely necessary
actions, like cleaning up alternates, for example.
For compose mode hooks that may affect the message content please
see on-compose-enter, on-compose-leave, on-compose-splice. [v15
behaviour may differ] This hook exists because alias, alternates,
commandalias, shortcut, to name a few, are neither covered by
localopts nor by local: changes applied in compose mode will con-
tinue to be in effect thereafter.
on-compose-enter, on-compose-leave
Macro hooks which will be called once compose mode is entered, and
after composing has been finished, respectively; the exact order of
the steps taken is documented for ~., one of the COMMAND ESCAPES.
Context about the message being worked on can be queried via
digmsg. localopts are enabled for these hooks, and changes on
variables will be forgotten after the message has been sent.
on-compose-cleanup can be used to perform other necessary cleanup
steps.
Here is an example that injects a signature via
message-inject-tail; instead using on-compose-splice to simply
inject the file of desire via ~< or ~<! may be a better approach.
define t_ocl {
vput ! i cat ~/.mysig
if $? -eq 0
vput csop message-inject-tail trim-end $i
end
# Alternatively
readctl create ~/.mysig
if $? -eq 0
readall i
if $? -eq 0
vput csop message-inject-tail trim-end $i
end
readctl remove ~/.mysig
end
}
set on-compose-leave=t_ocl
on-compose-splice, on-compose-splice-shell
These hooks run once the normal compose mode is finished, but
before the on-compose-leave macro hook is called etc. Both hooks
will be executed in a subprocess, with their input and output con-
nected to S-nail such that they can act as if they would be an
interactive user. The difference in between them is that the lat-
ter is a SHELL command, whereas the former is a normal defined
macro, but which is restricted to a small set of commands (the
verbose output of for example list will indicate said capability).
localopts are enabled for these hooks (in the parent process),
causing any setting to be forgotten after the message has been
sent; on-compose-cleanup can be used to perform other cleanup as
necessary.
During execution of these hooks S-nail will temporarily forget
whether it has been started in interactive mode, (a restricted set
of) COMMAND ESCAPES will always be available, and for guaranteed
reproducibilities sake escape and ifs will be set to their
defaults. The compose mode command ~^ has been especially designed
for scriptability (via these hooks). The first line the hook will
read on its standard input is the protocol version of said command
escape, currently ``0 0 2'': backward incompatible protocol changes
have to be expected.
Care must be taken to avoid deadlocks and other false control flow:
if both involved processes wait for more input to happen at the
same time, or one does not expect more input but the other is stuck
waiting for consumption of its output, etc. There is no automatic
synchronization of the hook: it will not be stopped automatically
just because it, e.g., emits `~x'. The hooks will however receive
a termination signal if the parent enters an error condition. [v15
behaviour may differ] Protection against and interaction with sig-
nals is not yet given; it is likely that in the future these
scripts will be placed in an isolated session, which is signalled
in its entirety as necessary.
define ocs_signature {
read version
echo '~< ~/.mysig' # '~<! fortune pathtofortunefile'
}
set on-compose-splice=ocs_signature
wysh set on-compose-splice-shell=$'\
read version;\
printf "hello $version! Headers: ";\
echo \'~^header list\';\
read status result;\
echo "status=$status result=$result";\
'
define ocsm {
read version
echo Splice protocol version is $version
echo '~^h l'; read hl; vput csop es subs "${hl}" 0 1
if "$es" != 2
echoerr 'Cannot read header list'; echo '~x'; xit
endif
if "$hl" !%?case ' cc'
echo '~^h i cc "Diet is your <mirr.or>"'; read es;\
vput csop es substring "${es}" 0 1
if "$es" != 2
echoerr 'Cannot insert Cc: header'; echo '~x'
# (no xit, macro finishes anyway)
endif
endif
}
set on-compose-splice=ocsm
on-history-addition
This hook will be called if an entry is about to be added to the
history of the MLE, as documented in On terminal control and line
editor. It will be called with three arguments: the first is the
name of the input context (see bind), the second is either an empty
string or the matching history-gabby type, and the third being the
complete command line to be added. The entry will not be added to
history if the hook uses a non-0 return. [v15 behaviour may dif-
fer] A future version will give the expanded command name as the
third argument, followed by the tokenized command line as parsed in
the remaining arguments, the first of which is the original unex-
panded command name; i.e., one may do `shift 4' and will then be
able to access the positional parameters as usual via *, #, 1 etc.
on-main-loop-tick
This hook will be called whenever the program's main event loop is
about to read the next input line. Note variable and other changes
it performs are not scoped as via localopts!
on-program-exit
This hook will be called when the program exits, whether via exit
or quit, or because the send mode is done. Note: this runs late
and so terminal settings etc. are already teared down.
on-resend-cleanup
[v15 behaviour may differ] Identical to on-compose-cleanup, but is
only triggered by resend.
on-resend-enter
[v15 behaviour may differ] Identical to on-compose-enter, but is
only triggered by resend; currently there is no digmsg support, for
example.
page (Boolean) If set, each message feed through the command given for
pipe is followed by a formfeed character `\f'.
password-USER@HOST, password-HOST, password
[v15-compat] Variable chain that sets a password, which is used in
case none has been given in the protocol and account-specific URL;
as a last resort S-nail will ask for a password on the user's ter-
minal if the authentication method requires a password. Specifying
passwords in a startup file is generally a security risk; the file
should be readable by the invoking user only.
password-USER@HOST
[no v15-compat] (see the chain above for [v15-compat]) Set the
password for `USER' when connecting to `HOST'. If no such variable
is defined for a host, the user will be asked for a password on
standard input. Specifying passwords in a startup file is gener-
ally a security risk; the file should be readable by the invoking
user only.
piperaw
(Boolean) Send messages to the pipe command without performing MIME
and character set conversions.
pipe-EXTENSION
Identical to pipe-TYPE/SUBTYPE except that `EXTENSION' (normalized
to lowercase using character mappings of the ASCII charset) denotes
a file extension, for example `xhtml'. Handlers registered using
this method take precedence.
pipe-TYPE/SUBTYPE
A MIME message part identified as `TYPE/SUBTYPE' (case-insensitive,
normalized to lowercase using character mappings of the ASCII
charset) is displayed or quoted, its text is filtered through the
value of this variable interpreted as a shell command. Unless
noted only parts displayable as inline plain text (see
copiousoutput) are covered, other MIME parts will only be consid-
ered by and for mimeview.
The special value question mark `?' forces interpretation of the
message part as plain text, for example `set
pipe-application/xml=?'. (This can also be achieved by adding a
MIME type-marker via mimetype.) [Option]ally MIME type handlers
may be defined via The Mailcap files to which should be referred to
for documentation of flags like copiousoutput. Question mark is
indeed a trigger character to indicate flags that adjust behaviour
and usage of the rest of the value, the shell command, for example:
? set pipe-X/Y='?!++=? vim ${MAILX_FILENAME_TEMPORARY}'
`*' The command output can be reintegrated into this MUA's normal
processing: copiousoutput. Implied when using a plain `'.
`#' Only use this handler for display, not for quoting a message:
x-mailx-noquote.
`&' Run the command asynchronously, do not wait for the handler
to exit: x-mailx-async. The standard output of the command
will go to /dev/null.
`!' The command must be run on an interactive terminal, the ter-
minal will temporarily be released for it to run:
needsterminal.
`+' Request creation of a zero-sized temporary file, the absolute
pathname of which will be made accessible via the environment
variable MAILX_FILENAME_TEMPORARY: x-mailx-tmpfile. If given
twice then the file will be unlinked automatically by S-nail
when the command loop is entered again at latest:
x-mailx-tmpfile-unlink; it is an error to use automatic dele-
tion in conjunction with x-mailx-async.
`=' Normally the MIME part content is passed to the handler via
standard input; with this the data will instead be written
into MAILX_FILENAME_TEMPORARY (x-mailx-tmpfile-fill), the
creation of which is implied; in order to cause automatic
deletion of the temporary file two plus signs `++' still have
to be used.
`t' Text type-marker: display this as normal plain text (for
type-markers: The mime.types files). Identical to only giv-
ing plain `?', implies copiousoutput.
`h' [Option] HTML type-marker: display via built-in HTML-to-text
filter. Implies copiousoutput.
`?' To avoid ambiguities with normal shell command content
another question mark can be used to forcefully terminate
interpretation of remaining characters. (Any character not
in this list will have the same effect.)
Some information about the MIME part to be displayed is embedded
into the environment of the shell command:
MAILX_CONTENT The MIME content-type of the part, if
known, the empty string otherwise.
MAILX_CONTENT_EVIDENCE If mime-counter-evidence includes the
carry-around-bit (2), then this will be
set to the detected MIME content-type; not
only then identical to MAILX_CONTENT oth-
erwise.
MAILX_EXTERNAL_BODY_URL MIME parts of type `message/external-body
access-type=url' will store the access URL
in this variable, it is empty otherwise.
URL targets should not be activated auto-
matically, without supervision.
MAILX_FILENAME The filename, if any is set, the empty
string otherwise.
MAILX_FILENAME_GENERATED
A random string.
MAILX_FILENAME_TEMPORARY
If temporary file creation has been
requested through the command prefix this
variable will be set and contain the abso-
lute pathname of the temporary file.
pop3-auth-USER@HOST, pop3-auth-HOST, pop3-auth
[Option][v15-compat] Variable chain that sets the POP3 authentica-
tion method. Supported are the default `plain', [v15-compat]
`oauthbearer' (see FAQ entry But, how about XOAUTH2 /
OAUTHBEARER?), as well as [v15-compat] `external' and `externanon'
for TLS secured connections which pass a client certificate via
tls-config-pairs. There may be the [Option]al method [v15-compat]
`gssapi'. `externanon' does not need any user credentials,
`external' and `gssapi' need a user, the remains also require a
password. `externanon' solely builds upon the credentials passed
via a client certificate, and is usually the way to go since tested
servers do not actually follow RFC 4422, and fail if additional
credentials are actually passed. Unless pop3-no-apop is set the
`plain' method will [Option]ally be replaced with APOP if possible
(see there).
pop3-bulk-load-USER@HOST, pop3-bulk-load-HOST, pop3-bulk-load
(Boolean)[Option] When accessing a POP3 server S-nail loads the
headers of the messages, and only requests the message bodies on
user request. For the POP3 protocol this means that the message
headers will be downloaded twice. If this variable is set then
S-nail will download only complete messages from the given POP3
server(s) instead.
pop3-keepalive-USER@HOST, pop3-keepalive-HOST, pop3-keepalive
[Option] POP3 servers close the connection after a period of inac-
tivity; the standard requires this to be at least 10 minutes, but
practical experience may vary. Setting this variable to a numeric
value greater than `0' causes a `NOOP' command to be sent each
value seconds if no other operation is performed.
pop3-no-apop-USER@HOST, pop3-no-apop-HOST, pop3-no-apop
(Boolean)[Option] Unless this variable is set the MD5 based `APOP'
authentication method will be used instead of a chosen `plain'
pop3-auth when connecting to a POP3 server that advertises support.
The advantage of `APOP' is that only a single packet is sent for
the user/password tuple. (Originally also that the password is not
sent in clear text over the wire, but for one MD5 does not any
longer offer sufficient security, and then today transport is
almost ever TLS secured.) Note that pop3-no-apop-HOST requires
[v15-compat].
pop3-use-starttls-USER@HOST, pop3-use-starttls-HOST, pop3-use-starttls
(Boolean)[Option] Causes S-nail to issue a `STLS' command to make
an unencrypted POP3 session TLS encrypted. This functionality is
not supported by all servers, and is not used if the session is
already encrypted by the POP3S method. Note that
pop3-use-starttls-HOST requires [v15-compat].
posix
(Boolean) This flag enables POSIX mode, which changes behaviour of
S-nail where that deviates from standardized behaviour. It is
automatically squared with the environment variable
POSIXLY_CORRECT, changing the one will adjust the other. The fol-
lowing behaviour is covered and enforced by this mechanism:
o In non-interactive mode, any error encountered while loading
resource files during program startup will cause a program
exit, whereas in interactive mode such errors will stop loading
of the currently loaded (stack of) file(s, i.e., recursively).
These exits can be circumvented on a per-command base by using
ignerr, one of the Command modifiers, for each command which
shall be allowed to fail.
o alternates will replace the list of alternate addresses instead
of appending to it. In addition alternates will only be hon-
oured for any sort of message reply, and for aliases.
o The variable inserting COMMAND ESCAPES ~A, ~a, ~I and ~i will
expand embedded character sequences `\t' horizontal tabulator
and `\n' line feed. [v15 behaviour may differ] For compatibil-
ity reasons this step will always be performed.
o Reading in messages via ~f (COMMAND ESCAPES) will use the
`type' not the `forward' headerpick selection.
o Upon changing the active folder no summary of headers will be
displayed even if header is set.
o Setting ignoreeof implies the behaviour described by dot.
o The variable keep is extended to cover any empty mailbox, not
only empty primary system mailboxes: they will be removed when
they are left in empty state otherwise.
o Each command has an exit ? and error ! status that overwrites
that of the last command. In POSIX mode the program exit sta-
tus will signal failure regardless unless all messages were
successfully sent out to the mta; also see sendwait.
print-alternatives
(Boolean) When a MIME message part of type `multipart/alternative'
is displayed and it contains a subpart of type `text/plain', other
parts are normally discarded. Setting this variable causes all
subparts to be displayed, just as if the surrounding part was of
type `multipart/mixed'.
prompt
The string used as a prompt in interactive mode. Whenever the
variable is evaluated the value is treated as if specified within
dollar-single-quotes (see Shell-style argument quoting). This
(post-assignment, i.e., second) expansion can be used to embed sta-
tus information, for example ?, !, account or mailbox-display.
In order to embed characters which should not be counted when cal-
culating the visual width of the resulting string, enclose the
characters of interest in a pair of reverse solidus escaped brack-
ets: `\[\E[0m\]'; a slot for coloured prompts is also available
with the [Option]al command colour. Prompting may be prevented by
setting this to the null string (aka `set noprompt').
prompt2
This string is used for secondary prompts, but is otherwise identi-
cal to prompt. The default is `.. '.
quiet
(Boolean) Suppresses the printing of the version when first
invoked.
quote
If set messages processed by variants of followup and reply will
start with the original message, lines of which prefixed by
indentprefix, taking into account quote-chars and quote-fold. No
headers will be quoted when set without value or for `noheading',
for `headers' the `type' headerpick selection will be included in
the quote, `allbodies' embeds the (body) contents of all MIME
parts, and `allheaders' also includes all headers. The quoted mes-
sage will be enclosed by the expansions of quote-inject-head and
quote-inject-tail. Also see quote-add-cc, quote-as-attachment and
~Q, one of the COMMAND ESCAPES.
quote-add-cc
(Boolean) Whether senders of messages quoted via ~Q shall be made
members of the carbon copies `Cc:' list.
quote-as-attachment
(Boolean) Add the original message in its entirety as a
`message/rfc822' MIME attachment when replying to a message. Note
this works regardless of the setting of quote.
quote-chars
Can be set to a string consisting of non-whitespace ASCII charac-
ters which shall be treated as quotation leaders, the default being
`>|}:'.
quote-fold
[Option] Can be set in addition to indentprefix, and creates a more
fancy quotation in that leading quotation characters (quote-chars)
are compressed and overlong lines are folded. quote-fold can be
set to either one, two or three (space separated) numeric values,
which are interpreted as the maximum (goal) and the minimum line
length, respectively, in a spirit rather equal to the fmt(1) pro-
gram, but line- instead of paragraph-based. The third value is
used as the maximum line length instead of the first if no better
break point can be found; it is ignored unless it is larger than
the minimum and smaller than the maximum. If not set explicitly
the minimum will reflect the goal algorithmically. The goal cannot
be smaller than the length of indentprefix plus some additional
pad; necessary adjustments take place silently.
quote-inject-head, quote-inject-tail
The strings to put before and after the text of a quoted message,
if non-empty, and respectively. The former defaults to `%f
wrote:\n\n'. Special format directives will be expanded if possi-
ble, and if so configured the output will be folded according to
quote-fold. Format specifiers in the given strings start with a
percent sign `%' and expand values of the original message, unless
noted otherwise. Note that names and addresses are not subject to
the setting of showto. Valid format specifiers are:
`%%' A plain percent sign.
`%a' The address(es) of the sender(s).
`%d' The date found in the `Date:' header of the message when
datefield is set (the default), otherwise the date when the
message was received. Formatting can be controlled by
assigning a strftime(3) format string to datefield (and
datefield-markout-older).
`%f' The full name(s) (name and address, as given) of the
sender(s).
`%i' The `Message-ID:'.
`%n' The real name(s) of the sender(s) if there is one and
showname allows usage, the address(es) otherwise.
`%r' The senders real name(s) if there is one, the address(es)
otherwise.
r-option-implicit
(Boolean) Setting this option evaluates the contents of from (or,
if that contains multiple addresses, sender) and passes the results
onto the used (file-based) MTA as described for the -r option
(empty argument case).
recipients-in-cc
(Boolean) When doing a reply, the original `From:' and `To:' as
well as addressees which possibly came in via `Reply-To:' and
`Mail-Followup-To:' are by default merged into the new `To:'. If
this variable is set a sensitive algorithm tries to place in `To:'
only the sender of the message being replied to, others are placed
in `Cc:'.
record
Unless this variable is defined, no copies of outgoing mail will be
saved. If defined it gives the pathname, subject to the usual
Filename transformations, of a folder where all new, replied-to or
forwarded messages are saved: when saving to this folder fails the
message is not sent, but instead saved to DEAD. The standard
defines that relative (fully expanded) paths are to be interpreted
relative to the current directory (cwd), to force interpretation
relative to folder outfolder needs to be set in addition.
record-files
(Boolean) If this variable is set the meaning of record will be
extended to cover messages which target only file and pipe recipi-
ents (see expandaddr). These address types will not appear in
recipient lists unless add-file-recipients is also set.
record-resent
(Boolean) If this variable is set the meaning of record will be
extended to also cover the resend and Resend commands.
reply-in-same-charset
(Boolean) If this variable is set S-nail first tries to use the
same character set of the original message for replies. If this
fails, the mechanism described in Character sets is evaluated as
usual.
reply-strings
Can be set to a comma-separated list of (case-insensitive according
to ASCII rules) strings which shall be recognized in addition to
the built-in strings as `Subject:' reply message indicators -
built-in are `Re:', which is mandated by RFC 5322, as well as the
german `Aw:', `Antw:', and the `Wg:' which often has been seen in
the wild; I.e., the separating colon has to be specified explic-
itly.
reply-to
A list of addresses to put into the `Reply-To:' field of the mes-
sage header. Members of this list are handled as if they were in
the alternates list.
replyto
[Obsolete] Variant of reply-to.
reply-to-honour
Controls whether a `Reply-To:' header is honoured when replying to
a message via reply or Lreply. This is a quadoption; if set with-
out a value it defaults to ``yes''.
reply-to-swap-in
Standards like DKIM and (in conjunction with) DMARC caused many
Mailing lists to use sender address rewriting in the style of `Name
via List <list@address>', where the original sender address often
being placed in `Reply-To:'. If this is set and a `Reply-To:'
exists, and consists of only one addressee (!), then that is used
in place of the pretended sender. This works independently from
reply-to-honour. The optional value, a comma-separated list of
strings, offers more fine-grained control on when swapping shall be
used; for now supported is mlist, here swapping occurs if the
sender is a mailing-list as defined by mlist.
rfc822-body-from_
(Boolean) This variable can be used to force displaying a so-called
`From_' line for messages that are embedded into an envelope mail
via the `message/rfc822' MIME mechanism, for more visual conve-
nience, also see mbox-rfc4155.
save (Boolean) Enable saving of (partial) messages in DEAD upon inter-
rupt or delivery error.
screen
The number of lines that represents a ``screenful'' of lines, used
in headers summary display, from searching, message topline display
and scrolling via z. If this variable is not set S-nail falls back
to a calculation based upon the detected terminal window size and
the baud rate: the faster the terminal, the more will be shown.
Overall screen dimensions and pager usage is influenced by the
environment variables COLUMNS and LINES and the variable crt.
searchheaders
(Boolean) Expand message list specifiers in the form `/x:y' to all
messages containing the substring ``y'' in the header field `x'.
The string search is case insensitive.
sendcharsets
[Option] A comma-separated list of character set names that can be
used in outgoing internet mail. The value of the variable
charset-8bit is automatically appended to this list of character
sets. If no character set conversion capabilities are compiled
into S-nail then the only supported charset is ttycharset. Also
see sendcharsets-else-ttycharset and refer to the section Character
sets for the complete picture of character set conversion in
S-nail.
sendcharsets-else-ttycharset
(Boolean)[Option] If this variable is set, but sendcharsets is not,
then S-nail acts as if sendcharsets had been set to the value of
the variable ttycharset. In effect this combination passes through
the message data in the character set of the current locale encod-
ing: therefore mail message text will be (assumed to be) in
ISO-8859-1 encoding when send from within a ISO-8859-1 locale, and
in UTF-8 encoding when send from within an UTF-8 locale.
The 8-bit fallback charset-8bit never comes into play as ttycharset
is implicitly assumed to be 8-bit and capable to represent all
files the user may specify (as is the case when no character set
conversion support is available in S-nail and the only supported
character set is ttycharset, see Character sets). This might be a
problem for scripts which use the suggested `LC_ALL=C' setting,
since in this case the character set is US-ASCII by definition, so
that it is better to also override ttycharset, then; and/or do
something like the following in the resource file:
# Avoid ASCII "propagates to 8-bit" when scripting
\if ! t && "$LC_ALL" != C && "$LC_CTYPE" != C
\set sendcharsets-else-ttycharset
\end
sender
An address that is put into the `Sender:' field of outgoing mes-
sages, quoting RFC 5322: the mailbox of the agent responsible for
the actual transmission of the message. This field should normally
not be used unless the from field contains more than one address,
on which case it is required. [v15 behaviour may differ] Please
expect automatic management of the from and sender relationship.
Dependent on the context this address is handled as if it were in
the list of alternates. Also see -r, r-option-implicit.
sendmail
[Obsolete] Predecessor of mta.
sendmail-arguments
[Obsolete] Predecessor of mta-arguments.
sendmail-no-default-arguments
[Obsolete](Boolean) Predecessor of mta-no-default-arguments.
sendmail-progname
[Obsolete] Predecessor of mta-argv0.
sendwait
Sending messages to the chosen mta or to command-pipe receivers
(see On sending mail, and non-interactive mode) will be performed
asynchronously. This means that only startup errors of the respec-
tive program will be recognizable, but no delivery errors. Also,
no guarantees can be made as to when the respective program will
actually run, as well as to when they will have produced output.
If this variable is set then child program exit is waited for, and
its exit status code is used to decide about success. Remarks: in
conflict with the POSIX standard this variable is built-in to be
initially set. Another difference is that it can have a value,
which is interpreted as a comma-separated list of case-insensitive
strings naming specific subsystems for which synchronousness shall
be ensured (only). Possible values are `mta' for mta delivery, and
`pcc' for command-pipe receivers.
showlast
(Boolean) This setting causes S-nail to start at the last message
instead of the first one when opening a mail folder, as well as
with from and headers.
showname
(Boolean) Causes S-nail to use the sender's real name instead of
the plain address in the header field summary and in message speci-
fications.
showto
(Boolean) Causes the recipient of the message to be shown in the
header summary if the message was sent by the user.
Sign The value backing ~A, one of the COMMAND ESCAPES. Also see
message-inject-tail, on-compose-leave and on-compose-splice.
sign The value backing ~a, one of the COMMAND ESCAPES. Also see
message-inject-tail, on-compose-leave and on-compose-splice.
signature
[Obsolete] Please use on-compose-splice or on-compose-splice-shell
or on-compose-leave and (if necessary) message-inject-tail instead!
skipemptybody
(Boolean) If an outgoing message has an empty first or only message
part, do not send, but discard it, successfully (also see the com-
mand line option -E).
smime-ca-dir, smime-ca-file
[Option] Specify the location of trusted CA certificates in PEM
(Privacy Enhanced Mail) for the purpose of verification of S/MIME
signed messages. tls-ca-dir documents the necessary preparation
steps to use the former. The set of CA certificates which are
built into the TLS library can be explicitly turned off by setting
smime-ca-no-defaults, and further fine-tuning is possible via
smime-ca-flags.
smime-ca-flags
[Option] Can be used to fine-tune behaviour of the X509 CA certifi-
cate storage, and the certificate verification that is used. The
actual values and their meanings are documented for tls-ca-flags.
smime-ca-no-defaults
(Boolean)[Option] Do not load the default CA locations that are
built into the used to TLS library to verify S/MIME signed mes-
sages.
smime-cipher-USER@HOST, smime-cipher
[Option] Specifies the cipher to use when generating S/MIME
encrypted messages (for the specified account). RFC 5751 mandates
a default of `aes128' (AES-128 CBC). Possible values are (case-
insensitive and) in decreasing cipher strength: `aes256' (AES-256
CBC), `aes192' (AES-192 CBC), `aes128' (AES-128 CBC), `des3' (DES
EDE3 CBC, 168 bits; default if `aes128' is not available) and `des'
(DES CBC, 56 bits).
The actually available cipher algorithms depend on the crypto-
graphic library that S-nail uses. [Option] Support for more cipher
algorithms may be available through dynamic loading via
EVP_get_cipherbyname(3) (OpenSSL) if S-nail has been compiled to
support this.
smime-crl-dir
[Option] Specifies a directory that contains files with CRLs in PEM
format to use when verifying S/MIME messages.
smime-crl-file
[Option] Specifies a file that contains a CRL in PEM format to use
when verifying S/MIME messages.
smime-encrypt-USER@HOST
[Option] If this variable is set, messages send to the given
receiver are encrypted before sending. The value of the variable
must be set to the name of a file that contains a certificate in
PEM format.
If a message is sent to multiple recipients, each of them for whom
a corresponding variable is set will receive an individually
encrypted message; other recipients will continue to receive the
message in plain text unless the smime-force-encryption variable is
set. It is recommended to sign encrypted messages, i.e., to also
set the smime-sign variable. content-description-smime-message
will be inspected for messages which become encrypted.
smime-force-encryption
(Boolean)[Option] Causes S-nail to refuse sending unencrypted mes-
sages.
smime-sign
(Boolean)[Option] S/MIME sign outgoing messages with the user's
(from) private key and include the users certificate as a MIME
attachment. Signing a message enables a recipient to verify that
the sender used a valid certificate, that the email addresses in
the certificate match those in the message header and that the mes-
sage content has not been altered. It does not change the message
text, and people will be able to read the message as usual.
content-description-smime-signature will be inspected. Also see
smime-sign-cert, smime-sign-include-certs and smime-sign-digest.
smime-sign-cert-USER@HOST, smime-sign-cert
[Option] Points to a file in PEM format. For the purpose of sign-
ing and decryption this file needs to contain the user's private
key, followed by his certificate.
For message signing `USER@HOST' is always derived from the value of
from (or, if that contains multiple addresses, sender). For the
purpose of encryption the recipients public encryption key (cer-
tificate) is expected; the command certsave can be used to save
certificates of signed messages (the section Signed and encrypted
messages with S/MIME gives some details). This mode of operation
is usually driven by the specialized form.
When decrypting messages the account is derived from the recipient
fields (`To:' and `Cc:') of the message, which are searched for
addresses for which such a variable is set. S-nail always uses the
first address that matches, so if the same message is sent to more
than one of the user addresses using different encryption keys,
decryption might fail.
Password-encrypted keys may be used for signing and decryption.
Automated password lookup is possible via the ``pseudo-hosts''
`USER AT HOST.smime-cert-key' for the private key, and
`USER AT HOST.smime-cert-cert' for the certificate stored in the same
file. For example, the hypothetical address `bob AT exam.ple' could
be driven with a private key / certificate pair path defined in
smime-sign-cert-bob AT exam.ple, and the needed passwords would then
be looked up as `bob AT exam.smime-cert-key' and
`bob AT exam.smime-cert-cert'. When decrypting the value of from
will be tried as a fallback to provide the necessary `USER@HOST'.
To include intermediate certificates, use smime-sign-include-certs.
The possible password sources are documented in On URL syntax and
credential lookup.
smime-sign-digest-USER@HOST, smime-sign-digest
[Option] Specifies the message digest to use when signing S/MIME
messages. Please remember that for this use case `USER@HOST'
refers to the variable from (or, if that contains multiple
addresses, sender). The available algorithms depend on the used
cryptographic library, but at least one usable built-in algorithm
is ensured as a default. If possible the standard RFC 5751 will be
violated by using `SHA512' instead of the mandated `SHA1' due to
security concerns. This variable is ignored for very old (released
before 2010) cryptographic libraries which do not offer the neces-
sary interface: it will be logged if that happened.
S-nail will try to add built-in support for the following message
digests, names are case-insensitive: `BLAKE2b512', `BLAKE2s256',
`SHA3-512', `SHA3-384', `SHA3-256', `SHA3-224', as well as the
widely available `SHA512', `SHA384', `SHA256', `SHA224', and the
proposed insecure `SHA1', finally `MD5'. More digests may
[Option]ally be available through dynamic loading via the OpenSSL
function EVP_get_digestbyname(3).
smime-sign-include-certs-USER@HOST, smime-sign-include-certs
[Option] If used, this is supposed to a consist of a comma-sepa-
rated list of files, each of which containing a single certificate
in PEM format to be included in the S/MIME message in addition to
the smime-sign-cert certificate. This can be used to include
intermediate certificates of the certificate authority, in order to
allow the receiver's S/MIME implementation to perform a verifica-
tion of the entire certificate chain, starting from a local root
certificate, over the intermediate certificates, down to the
smime-sign-cert. Even though top level certificates may also be
included in the chain, they will not be used for the verification
on the receiver's side.
For the purpose of the mechanisms involved here, `USER@HOST' refers
to the content of the internal variable from (or, if that contains
multiple addresses, sender). The pseudo-host
`USER AT HOST.smime-include-certs' will be used for performing pass-
word lookups for these certificates, shall they have been given
one, therefore the lookup can be automated via the mechanisms
described in On URL syntax and credential lookup.
smime-sign-message-digest-USER@HOST, smime-sign-message-digest
[Obsolete][Option] Predecessor(s) of smime-sign-digest.
smtp [Obsolete][Option] To use the built-in SMTP transport, specify a
SMTP URL in mta. [v15 behaviour may differ] For compatibility rea-
sons a set smtp is used in preference of mta.
smtp-auth-USER@HOST, smtp-auth-HOST, smtp-auth
[Option] Variable chain that controls the SMTP mta authentication
method, possible values are `none' ([no v15-compat] default),
`plain' ([v15-compat] default), `login', [v15-compat] `oauthbearer'
(see FAQ entry But, how about XOAUTH2 / OAUTHBEARER?) as well as
[v15-compat] `external' and `externanon' for TLS secured connec-
tions which pass a client certificate via tls-config-pairs. There
may be the [Option]al methods `cram-md5' and `gssapi'. `none' and
`externanon' do not need any user credentials, `external' and
`gssapi' require a user name, and all other methods require a user
name and a password. `externanon' solely builds upon the creden-
tials passed via a client certificate, and is usually the way to go
since tested servers do not actually follow RFC 4422 aka RFC 4954,
and fail if additional credentials are passed. Also see mta. Note
that smtp-auth-HOST is [v15-compat]. ([no v15-compat] Requires
smtp-auth-password and smtp-auth-user. Note for
smtp-auth-USER@HOST: may override dependent on sender address in
the variable from.)
smtp-auth-password
[Option][no v15-compat] Sets the global fallback password for SMTP
authentication. If the authentication method requires a password,
but neither smtp-auth-password nor a matching
smtp-auth-password-USER@HOST can be found, S-nail will ask for a
password on the user's terminal.
smtp-auth-password-USER@HOST
[no v15-compat] Overrides smtp-auth-password for specific values of
sender addresses, dependent upon the variable from.
smtp-auth-user
[Option][no v15-compat] Sets the global fallback user name for SMTP
authentication. If the authentication method requires a user name,
but neither smtp-auth-user nor a matching smtp-auth-user-USER@HOST
can be found, S-nail will ask for a user name on the user's termi-
nal.
smtp-auth-user-USER@HOST
[no v15-compat] Overrides smtp-auth-user for specific values of
sender addresses, dependent upon the variable from.
smtp-hostname
[Option][v15-compat] Normally S-nail uses the variable from to
derive the necessary `USER@HOST' information in order to issue a
`MAIL FROM:<>' SMTP mta command. Setting smtp-hostname can be used
to use the `USER' from the SMTP account (mta or the user variable
chain) and the given `HOST' (hostname if the empty string is given,
or the local hostname as a last resort). This often allows using
an address that is itself valid but hosted by a provider other than
from which (in from) the message is sent. Setting this variable
also influences generated `Message-ID:' and `Content-ID:' header
fields. If the [Option]al IDNA support is available (see
idna-disable) variable assignment is aborted when a necessary con-
version fails.
smtp-use-starttls-USER@HOST, smtp-use-starttls-HOST, smtp-use-starttls
(Boolean)[Option] Causes S-nail to issue a `STARTTLS' command to
make an SMTP mta session TLS encrypted, i.e., to enable transport
layer security.
socket-connect-timeout
[Option] A positive number that defines the timeout to wait for
establishing a socket connection before forcing ^ERR-TIMEDOUT.
socks-proxy-USER@HOST, socks-proxy-HOST, socks-proxy
[Option] If set to the URL of a SOCKS5 server then all network
activities are proxied through it, except for the single DNS name
lookup necessary to resolve the proxy URL (unnecessary when given
an already resolved IP address). It is automatically squared with
the environment variable SOCKS5_PROXY, changing the one will adjust
the other. This example creates a local SOCKS5 proxy on port 10000
that forwards to the machine `HOST' (with identity `USER'), and
from which actual network traffic happens:
$ ssh -D 10000 USER@HOST
$ s-nail -Ssocks-proxy=[socks5://]localhost:10000
# or =localhost:10000; no local DNS: =127.0.0.1:10000
spam-interface
[Option] In order to use any of the spam-related commands (like
spamrate) the desired spam interface must be defined by setting
this variable. Please refer to the manual section Handling spam
for the complete picture of spam handling in S-nail. All or none
of the following interfaces may be available:
`spamc' Interaction with spamc(1) from the spamassassin(1)
(http://spamassassin.apache.org SpamAssassin) suite.
Different to the generic filter interface S-nail will
automatically add the correct arguments for a given com-
mand and has the necessary knowledge to parse the pro-
gram's output. A default value for spamc-command will
have been compiled into the S-nail binary if spamc(1) has
been found in PATH during compilation. Shall it be nec-
essary to define a specific connection type (rather than
using a configuration file for that), the variable
spamc-arguments can be used as in for example `-d
server.example.com -p 783'. It is also possible to spec-
ify a per-user configuration via spamc-user. Note that
this interface does not inspect the `is-spam' flag of a
message for the command spamforget.
`filter' generic spam filter support via freely configurable
hooks. This interface is meant for programs like
bogofilter(1) and requires according behaviour in respect
to the hooks' exit status for at least the command
spamrate (`0' meaning a message is spam, `1' for non-
spam, `2' for unsure and any other return value indicat-
ing a hard error); since the hooks can include shell code
snippets diverting behaviour can be intercepted as neces-
sary. The hooks are spamfilter-ham, spamfilter-noham,
spamfilter-nospam, spamfilter-rate and spamfilter-spam;
the manual section Handling spam contains examples for
some programs. The process environment of the hooks will
have the variable MAILX_FILENAME_GENERATED set. Note
that spam score support for spamrate is not supported
unless the [Option]tional regular expression support is
available and the spamfilter-rate-scanscore variable is
set.
spam-maxsize
[Option] Messages that exceed this size will not be passed through
to the configured spam-interface. If unset or 0, the default of
420000 bytes is used.
spamc-command
[Option] The path to the spamc(1) program for the `spamc'
spam-interface. Note that the path is not expanded, but used ``as
is''. A fallback path will have been compiled into the S-nail
binary if the executable had been found during compilation.
spamc-arguments
[Option] Even though S-nail deals with most arguments for the
`spamc' spam-interface automatically, it may at least sometimes be
desirable to specify connection-related ones via this variable, for
example `-d server.example.com -p 783'.
spamc-user
[Option] Specify a username for per-user configuration files for
the `spamc' spam-interface. If this is set to the empty string
then S-nail will use the name of the current user.
spamfilter-ham, spamfilter-noham, spamfilter-nospam, spamfilter-rate,
spamfilter-spam
[Option] Command and argument hooks for the `filter'
spam-interface. The manual section Handling spam contains examples
for some programs.
spamfilter-rate-scanscore
[Option] Because of the generic nature of the `filter'
spam-interface spam scores are not supported for it by default, but
if the [Option]nal regular expression support is available then
setting this variable can be used to overcome this restriction. It
is interpreted as follows: first a number (digits) is parsed that
must be followed by a semicolon `;' and an extended regular expres-
sion. Then the latter is used to parse the first output line of
the spamfilter-rate hook, and, in case the evaluation is success-
ful, the group that has been specified via the number is inter-
preted as a floating point scan score.
ssl-ca-dir-USER@HOST, ssl-ca-dir-HOST, ssl-ca-dir, ssl-ca-file-USER@HOST,
ssl-ca-file-HOST, ssl-ca-file
[Obsolete][Option] Predecessors of tls-ca-file, tls-ca-dir.
ssl-ca-flags-USER@HOST, ssl-ca-flags-HOST, ssl-ca-flags
[Obsolete][Option] Predecessor of tls-ca-flags.
ssl-ca-no-defaults-USER@HOST, ssl-ca-no-defaults-HOST, ssl-ca-no-defaults
[Obsolete](Boolean)[Option] Predecessor of tls-ca-no-defaults.
ssl-cert-USER@HOST, ssl-cert-HOST, ssl-cert
[Obsolete][Option] Please use the Certificate slot of
tls-config-pairs.
ssl-cipher-list-USER@HOST, ssl-cipher-list-HOST, ssl-cipher-list
[Obsolete][Option] Please use the CipherString slot of
tls-config-pairs.
ssl-config-file
[Obsolete][Option] Predecessor of tls-config-file.
ssl-config-module-USER@HOST, ssl-config-module-HOST, ssl-config-module
[Obsolete][Option] Predecessor of tls-config-module.
ssl-config-pairs-USER@HOST, ssl-config-pairs-HOST, ssl-config-pairs
[Obsolete][Option] Predecessor of tls-config-pairs.
ssl-crl-dir, ssl-crl-file
[Obsolete][Option] Predecessors of tls-crl-dir, tls-crl-file.
ssl-curves-USER@HOST, ssl-curves-HOST, ssl-curves
[Obsolete][Option] Please use the Curves slot of tls-config-pairs.
ssl-features
[Obsolete][Option](Read-only) Predecessor of tls-features.
ssl-key-USER@HOST, ssl-key-HOST, ssl-key
[Obsolete][Option] Please use the PrivateKey slot of
tls-config-pairs.
ssl-method-USER@HOST, ssl-method-HOST, ssl-method
[Obsolete][Option] Please use the Protocol slot of
tls-config-pairs.
ssl-protocol-USER@HOST, ssl-protocol-HOST, ssl-protocol
[Obsolete][Option] Please use the Protocol slot of
tls-config-pairs.
ssl-rand-file
[Obsolete][Option] Predecessor of tls-rand-file.
ssl-verify-USER@HOST, ssl-verify-HOST, ssl-verify
[Obsolete][Option] Predecessor of tls-verify.
stealthmua
If only set without an assigned value, then this setting inhibits
the generation of the `Message-ID:', `Content-ID:' and
`User-Agent:' header fields that include obvious references to
S-nail. There are two pitfalls associated with this: First, the
message id of outgoing messages is not known anymore. Second, an
expert may still use the remaining information in the header to
track down the originating mail user agent. If set to the value
`noagent', then the mentioned `Message-ID:' and `Content-ID:' sup-
pression does not occur.
system-mailrc
(Read-only) The compiled in path of the system wide initialization
file one of the Resource files: s-nail.rc.
termcap
([Option]) This specifies a comma-separated list of Terminal
Information Library (libterminfo, -lterminfo) and/or Termcap Access
Library (libtermcap, -ltermcap) capabilities (see On terminal
control and line editor, escape commas with reverse solidus `\') to
be used to overwrite or define entries. Note this variable will
only be queried once at program startup and can thus only be speci-
fied in resource files or on the command line. It will always be
inspected, regardless of whether features denotes termcap/terminfo
library support via `,+termcap,'.
String capabilities form `cap=value' pairs and are expected unless
noted otherwise. Numerics have to be notated as `cap#number' where
the number is expected in normal decimal notation. Finally, bool-
eans do not have any value but indicate a true or false state sim-
ply by being defined or not; this indeed means that S-nail does not
support undefining an existing boolean. String capability values
will undergo some expansions before use: for one notations like
`^LETTER' stand for `control-LETTER', and for clarification pur-
poses `\E' can be used to specify `escape' (the control notation
`^[' could lead to misreadings when a left bracket follows, which
it does for the standard CSI sequence); finally three letter octal
sequences, as in `\061', are supported. To specify that a terminal
supports 256-colours, and to define sequences that home the cursor
and produce an audible bell, one might write:
? set termcap='Co#256,home=\E[H,bel=^G'
The following terminal capabilities are or may be meaningful for
the operation of the built-in line editor or S-nail in general:
am auto_right_margin: boolean which indicates if the right margin
needs special treatment; the xenl capability is related, for
more see COLUMNS. This capability is only used when backed by
library support.
clear or cl
clear_screen: clear the screen and home cursor. (Will be sim-
ulated via ho plus cd.)
colors or Co
max_colors: numeric capability specifying the maximum number
of colours. Note that S-nail does not actually care about the
terminal beside that, but always emits ANSI / ISO 6429 escape
sequences; also see colour.
cr carriage_return: move to the first column in the current row.
The default built-in fallback is `\r'.
cub1 or le
cursor_left: move the cursor left one space (non-destruc-
tively). The default built-in fallback is `\b'.
cuf1 or nd
cursor_right: move the cursor right one space (non-destruc-
tively). The default built-in fallback is `\E[C', which is
used by most terminals. Less often occur `\EC' and `\EOC'.
ed or cd
clr_eos: clear the screen.
el or ce
clr_eol: clear to the end of line. (Will be simulated via ch
plus repetitions of space characters.)
home or ho
cursor_home: home cursor.
hpa or ch
column_address: move the cursor (to the given column parame-
ter) in the current row. (Will be simulated via cr plus nd.)
rmcup or te / smcup or ti
exit_ca_mode and enter_ca_mode, respectively: exit and enter
the alternative screen ca-mode, effectively turning S-nail
into a fullscreen application. This must be enabled explic-
itly by setting termcap-ca-mode.
smkx or ks / rmkx or ke
keypad_xmit and keypad_local, respectively: enable and disable
the keypad. This is always enabled if available, because it
seems even keyboards without keypads generate other key codes
for, e.g., cursor keys in that case, and only if enabled we
see the codes that we are interested in.
xenl or xn
eat_newline_glitch: boolean which indicates whether a newline
written in the last column of an auto_right_margin indicating
terminal is ignored. With it the full terminal width is
available even on autowrap terminals. This will be inspected
even without `,+termcap,' features.
Many more capabilities which describe key-sequences are documented
for bind.
termcap-ca-mode
[Option] Allow usage of the exit_ca_mode and enter_ca_mode
termcapabilities in order to enter an alternative exclusive screen,
the so-called ca-mode; this usually requires special configuration
of the PAGER, also dependent on the value of crt. Note this vari-
able will only be queried once at program startup and can thus only
be specified in resource files or on the command line.
termcap-disable
[Option] Disable any interaction with a terminal control library.
If set only some generic fallback built-ins and possibly the con-
tent of termcap describe the terminal to S-nail. Note this vari-
able will only be queried once at program startup and can thus only
be specified in resource files or on the command line.
tls-ca-dir-USER@HOST, tls-ca-dir-HOST, tls-ca-dir, tls-ca-file-USER@HOST,
tls-ca-file-HOST, tls-ca-file
[Option] Directory and file, respectively, for pools of trusted CA
certificates in PEM (Privacy Enhanced Mail) format, for the purpose
of verification of TLS server certificates. Concurrent use is pos-
sible, the file is loaded once needed first, the directory lookup
is performed anew as a last resort whenever necessary. The CA cer-
tificate pool built into the TLS library can be disabled via
tls-ca-no-defaults, further fine-tuning is possible via
tls-ca-flags. The directory search requires special filename con-
ventions, please see SSL_CTX_load_verify_locations(3) and verify(1)
(or c_rehash(1)).
tls-ca-flags-USER@HOST, tls-ca-flags-HOST, tls-ca-flags
[Option] Can be used to fine-tune behaviour of the X509 CA certifi-
cate storage, and the certificate verification that is used (also
see tls-verify). The value is expected to consist of a comma-sepa-
rated list of configuration directives, with any intervening white-
space being ignored. The directives directly map to flags that can
be passed to X509_STORE_set_flags(3), which are usually defined in
a file openssl/x509_vfy.h, and the availability of which depends on
the used TLS library version: a directive without mapping is
ignored (error log subject to debug). Directives currently under-
stood (case-insensitively) include:
no-alt-chains
If the initial chain is not trusted, do not attempt to build
an alternative chain. Setting this flag will make OpenSSL
certificate verification match that of older OpenSSL ver-
sions, before automatic building and checking of alternative
chains has been implemented; also see trusted-first.
no-check-time
Do not check certificate/CRL validity against current time.
partial-chain
By default partial, incomplete chains which cannot be veri-
fied up to the chain top, a self-signed root certificate,
will not verify. With this flag set, a chain succeeds to
verify if at least one signing certificate of the chain is in
any of the configured trusted stores of CA certificates. The
OpenSSL manual page SSL_CTX_load_verify_locations(3) gives
some advise how to manage your own trusted store of CA cer-
tificates.
strict
Disable workarounds for broken certificates.
trusted-first
Try building a chain using issuers in the trusted store first
to avoid problems with server-sent legacy intermediate cer-
tificates. Newer versions of OpenSSL support alternative
chain checking and enable it by default, resulting in the
same behaviour; also see no-alt-chains.
tls-ca-no-defaults-USER@HOST, tls-ca-no-defaults-HOST, tls-ca-no-defaults
(Boolean)[Option] Do not load the default CA locations that are
built into the used to TLS library to verify TLS server certifi-
cates.
tls-config-file
[Option] If this variable is set CONF_modules_load_file(3) (if
announced via `,+modules-load-file,' in tls-features) is used to
allow resource file based configuration of the TLS library. This
happens once the library is used first, which may also be early
during startup (logged with verbose)! If a non-empty value is
given then the given file, after performing Filename
transformations, will be used instead of the TLS libraries global
default, and it is an error if the file cannot be loaded. The
application name will always be passed as `s-nail'. Some TLS
libraries support application-specific configuration via resource
files loaded like this, please see tls-config-module.
tls-config-module-USER@HOST, tls-config-module-HOST, tls-config-module
[Option] If file based application-specific configuration via
tls-config-file is available, announced as `,+ctx-config,' by
tls-features, indicating availability of SSL_CTX_config(3), then,
it becomes possible to use a central TLS configuration file for all
programs, including s-nail, for example
# Register a configuration section for s-nail
s-nail = mailx_master
# The top configuration section creates a relation
# in between dynamic SSL configuration and an actual
# program specific configuration section
[mailx_master]
ssl_conf = mailx_tls_config
# And that program specific configuration section now
# can map diverse tls-config-module names to sections,
# as in: tls-config-module=account_xy
[mailx_tls_config]
account_xy = mailx_account_xy
account_yz = mailx_account_yz
[mailx_account_xy]
MinProtocol = TLSv1.2
Curves=P-521
[mailx_account_yz]
CipherString = TLSv1.2:!aNULL:!eNULL:
MinProtocol = TLSv1.1
Options = Bugs
tls-config-pairs-USER@HOST, tls-config-pairs-HOST, tls-config-pairs
[Option] The value of this variable chain will be interpreted as a
comma-separated list of directive/value pairs. Directives and val-
ues need to be separated by equals signs `=', any whitespace sur-
rounding pair members is removed. Keys are (usually) case-insensi-
tive. Different to when placing these pairs in a tls-config-module
section of a tls-config-file, commas `,' need to be escaped with a
reverse solidus `\' when included in pairs; also different: if the
equals sign `=' is preceded with an asterisk `*' Filename
transformations will be performed on the value; it is an error if
these fail. Unless proper support is announced by tls-features
(`,+conf-ctx,') only the keys below are supported, otherwise the
pairs will be used directly as arguments to the function
SSL_CONF_cmd(3).
Certificate Filename of a TLS client certificate (chain) required
by some servers. Fallback support via
SSL_CTX_use_certificate_chain_file(3). Filename
transformations are performed. PrivateKey will be
set to the same value if not initialized explicitly.
Some services support so-called `external' authenti-
cation if a TLS client certificate was successfully
presented during connection establishment
(``connecting is authenticating'').
CipherString A list of ciphers for TLS connections, see
ciphers(1). By default no list of ciphers is set,
resulting in a Protocol-specific list of ciphers (the
protocol standards define lists of acceptable
ciphers; possibly cramped by the used TLS library).
Fallback support via SSL_CTX_set_cipher_list(3).
Ciphersuites A list of ciphers used for TLSv1.3 connections, see
ciphers(1). These will be joined onto the list of
ciphers from CipherString. Available if tls-features
announces `,+ctx-set-ciphersuites,', as necessary via
SSL_CTX_set_ciphersuites(3).
Curves A list of supported elliptic curves, if applicable.
By default no curves are set. Fallback support via
SSL_CTX_set1_curves_list(3), if available.
MaxProtocol, MinProtocol
The maximum and minimum supported TLS versions,
respectively. Available if tls-features announces
`,+ctx-set-maxmin-proto,', as necessary via
SSL_CTX_set_max_proto_version(3) and
SSL_CTX_set_min_proto_version(3); these fallbacks use
an internal parser which understands the strings
`SSLv3', `TLSv1', `TLSv1.1', `TLSv1.2', `TLSv1.3',
and the special value `None', which disables the
given limit.
Options Various flags to set. Fallback via
SSL_CTX_set_options(3), in which case any other value
but (exactly) `Bugs' results in an error.
PrivateKey Filename of the private key in PEM format of a TLS
client certificate. If unset, the value of
Certificate is used. Filename transformations are
performed. Fallback via
SSL_CTX_use_PrivateKey_file(3).
Protocol The used TLS protocol. If tls-features announces
`,+conf-ctx,' or `ctx-set-maxmin-proto' then using
MaxProtocol and MinProtocol is preferable. Fallback
is SSL_CTX_set_options(3), driven via an internal
parser which understands the strings `SSLv3',
`TLSv1', `TLSv1.1', `TLSv1.2', `TLSv1.3', and the
special value `ALL'. Multiple protocols may be given
as a comma-separated list, any whitespace is ignored,
an optional plus sign `+' prefix enables, a hyphen-
minus `-' prefix disables a protocol, so that `-ALL,
TLSv1.2' enables only the TLSv1.2 protocol.
tls-crl-dir, tls-crl-file
[Option] Specify a directory / a file, respectively, that contains
a CRL in PEM format to use when verifying TLS server certificates.
tls-features
[Option](Read-only) This expands to a comma-separated list of the
TLS library identity and optional features. To ease substring
matching the string starts and ends with a comma. Currently sup-
ported identities are `libressl' (LibreSSL) , `libssl-0x30000'
(OpenSSL v3.0.0 series), `libssl-0x10100' (OpenSSL v1.1.x series)
and `libssl-0x10000' (elder OpenSSL series, other clones).
Optional features are preceded with a plus sign `+' when available,
and with a hyphen-minus `-' otherwise.
Currently known features are `conf-ctx' (tls-config-pairs),
`ctx-config' (tls-config-module), `ctx-set-ciphersuites'
(Ciphersuites slot of tls-config-pairs), `ctx-set-maxmin-proto'
(tls-config-pairs), `modules-load-file' (tls-config-file), and
`tls-rand-file' (tls-rand-file).
tls-fingerprint-USER@HOST, tls-fingerprint-HOST, tls-fingerprint
[Option] It is possible to replace the verification of the connec-
tion peer certificate against the entire local pool of CAs (for
more see Encrypted network communication) with the comparison
against a precalculated certificate message digest, the so-called
fingerprint, to be specified as the used tls-fingerprint-digest.
This fingerprint can for example be calculated with `tls
fingerprint HOST'.
tls-fingerprint-digest-USER@HOST, tls-fingerprint-digest-HOST,
tls-fingerprint-digest
[Option] The message digest to be used when creating TLS certifi-
cate fingerprints, the defaults, if available, in test order, being
`BLAKE2s256', `SHA256'. For the complete list of digest algorithms
refer to smime-sign-digest.
tls-rand-file
[Option] If tls-features announces `,+tls-rand-file,' then this
will be queried to find a file with random entropy data which can
be used to seed the P(seudo)R(andom)N(umber)G(enerator), see
RAND_load_file(3). The default filename (RAND_file_name(3), nor-
mally ~/.rnd) will be used if this variable is not set or empty, or
if the Filename transformations fail. Shall seeding the PRNG have
been successful, RAND_write_file(3) will be called to update the
entropy. Remarks: libraries which do not announce this feature
seed the PRNG by other means.
tls-verify-USER@HOST, tls-verify-HOST, tls-verify
[Option] Variable chain that sets the action to be performed if an
error occurs during TLS server certificate validation against the
specified or default trust stores tls-ca-dir, tls-ca-file, or the
TLS library built-in defaults (unless usage disallowed via
tls-ca-no-defaults), and as fine-tuned via tls-ca-flags. Valid
(case-insensitive) values are `strict' (fail and close connection
immediately), `ask' (ask whether to continue on standard input),
`warn' (show a warning and continue), `ignore' (do not perform val-
idation). The default is `ask'.
toplines
If defined, gives the number of lines of a message to be displayed
with the command top; if unset, the first five lines are printed,
if set to 0 the variable screen is inspected. If the value is neg-
ative then its absolute value will be used for unsigned right
shifting (see vexpr) the screen height.
topsqueeze
(Boolean) If set then the top command series will strip adjacent
empty lines and quotations.
ttycharset
The character set of the terminal S-nail operates on, and the one
and only supported character set that S-nail can use if no charac-
ter set conversion capabilities have been compiled into it, in
which case it defaults to ISO-8859-1. Otherwise it defaults to
UTF-8. Sufficient locale support provided the default will be
preferably deduced from the locale environment if that is set (for
example LC_CTYPE, see there for more); runtime locale changes will
be reflected by ttycharset except during the program startup phase
and if -S had been used to freeze the given value. Refer to the
section Character sets for the complete picture about character
sets.
typescript-mode
(Boolean) A special multiplex variable that disables all variables
and settings which result in behaviour that interferes with running
S-nail in script(1); it sets colour-disable, line-editor-disable
and (before startup completed only) termcap-disable. Unsetting it
does not restore the former state of the covered settings.
umask
For a safe-by-default policy the process file mode creation mask
umask(2) will be set to `0077' on program startup after the
resource files have been loaded, and unless this variable is set.
By assigning this an empty value the active setting will not be
changed, otherwise the given value will be made the new file mode
creation mask. Child processes inherit the file mode creation mask
of their parent.
user-HOST, user
[v15-compat] Variable chain that sets a global fallback user name,
used in case none has been given in the protocol and account-spe-
cific URL. This variable defaults to the name of the user who runs
S-nail.
v15-compat
Enable upward compatibility with S-nail version 15.0 in respect to
which configuration options are available and how they are handled.
If set to a non-empty value the command modifier wysh is implied
and thus enforces Shell-style argument quoting over Old-style
argument quoting for all commands which support both. This manual
uses [v15-compat] and [no v15-compat] to refer to the new and the
old way of doing things, respectively.
verbose
Verbose mode enables logging of informational context messages.
Historically a (Boolean) variable, this can either be set multiple
times (what the command line option -v uses), or be assigned a
numeric value in order to increase verbosity. Assigning the value
0 disables verbosity and thus (almost) equals unset. The maximum
number is 3. Also see debug.
version, version-date, version-hexnum, version-major, version-minor,
version-update
(Read-only) S-nail version information: the first variable is a
string with the complete version identification, the second the
release date in ISO 8601 notation without time. The third is a
32-bit hexadecimal number with the upper 8 bits storing the major,
followed by the minor and update version numbers which occupy 12
bits each. The latter three variables contain only decimal digits:
the major, minor and update version numbers. The output of the
command version will include this information.
writebackedited
If this variable is set messages modified using the edit or visual
commands are written back to the current folder when it is quit; it
is only honoured for writable folders in MBOX format, though. Note
that the editor will be pointed to the raw message content in that
case, i.e., neither MIME decoding nor decryption will have been
performed, and proper mbox-rfc4155 `From_' quoting of newly added
or edited content is also left as an exercise to the user.
ENVIRONMENT
The term ``environment variable'' should be considered an indication that
these variables are either standardized as vivid parts of process envi-
ronments, or that they are commonly found in there. The process environ-
ment is inherited from the sh(1) once S-nail is started, and unless oth-
erwise explicitly noted handling of the following variables transparently
integrates into that of the INTERNAL VARIABLES from S-nail's point of
view. This means they can be managed via set and unset, causing auto-
matic program environment updates (to be inherited by newly created child
processes).
In order to integrate other environment variables equally they need to be
imported (linked) with the command environ. This command can also be
used to set and unset non-integrated environment variables from scratch,
sufficient system support provided. The following example, applicable to
a POSIX shell, sets the COLUMNS environment variable for S-nail only, and
beforehand exports the EDITOR in order to affect any further processing
in the running shell:
$ EDITOR="vim -u ${HOME}/.vimrc"
$ export EDITOR
$ COLUMNS=80 s-nail -R
COLUMNS
The user's preferred width in column positions for the terminal
screen. Queried and used once on program startup in interactive or
batch (-#) mode, actively managed for child processes and the MLE
(see On terminal control and line editor) in interactive mode
thereafter. Non-interactive mode always uses, and the fallback
default is a compile-time constant, by default 80 columns. If in
batch mode COLUMNS and LINES are both set but not both are usable
(empty, not a number, or 0) at program startup, then the real ter-
minal screen size will be (tried to be) determined once. (Normally
the sh(1) manages these variables, and unsets them for pipe speci-
fications etc.)
DEAD The name of the (mailbox) folder to use for saving aborted messages
if save is set; this defaults to ~/dead.letter. If the variable
debug is set no output will be generated, otherwise the contents of
the file will be replaced. Except shell globs Filename
transformations (also see folder) will be performed.
EDITOR
Pathname of the text editor to use for the edit command and ~e
(see COMMAND ESCAPES); VISUAL is used for a more display oriented
editor.
HOME The user's home directory. This variable is only used when it
resides in the process environment. The calling user's home direc-
tory will be used instead if this directory does not exist, is not
accessible or cannot be read; it will always be used for the root
user. (No test for being writable is performed to allow usage by
non-privileged users within read-only jails, but dependent on set-
tings this directory is a default write target for, for example,
DEAD, MBOX and more.)
LC_ALL, LC_CTYPE, LANG
[Option] The (names in lookup order of the) locale(7) (and / or see
setlocale(3)) which indicates the used Character sets. Runtime
changes trigger automatic updates of the entire locale system,
which includes updating ttycharset (except during startup if the
variable has been frozen via -S).
LINES
The user's preferred number of lines for the terminal screen. The
behaviour is as described for COLUMNS, yet the compile-time con-
stant used in non-interactive mode and as a fallback defaults to 24
(lines).
LISTER
Pathname of the directory lister to use in the folders command when
operating on local mailboxes. Default is ls(1) (path search
through SHELL).
LOGNAME
Upon startup S-nail will actively ensure that this variable refers
to the name of the user who runs S-nail, in order to be able to
pass a verified name to any newly created child process.
MAIL Is used as the user's primary system mailbox unless inbox is set.
If the environmental fallback is also not set, a built-in compile-
time default is used. This is assumed to be an absolute pathname.
MAILCAPS
[Option] Override the default path search of The Mailcap files: any
existing file therein will be loaded in sequence, appending any
content to the list of MIME type handler directives. The RFC 1524
standard imposed default value is assigned otherwise: `~/.mailcap:
/etc/mailcap:/usr/etc/mailcap:/usr/local/etc/mailcap'. (The
default value is a compile-time [Option].)
MAILRC
Is used as a startup file instead of ~/.mailrc if set. In order to
avoid side-effects from configuration files scripts should either
set this variable to /dev/null or the -: command line option should
be used.
MAILX_NO_SYSTEM_RC
If this variable is set then reading of s-nail.rc (aka
system-mailrc) at startup is inhibited, i.e., the same effect is
achieved as if S-nail had been started up with the option -: (and
according argument) or -n. This variable is only used when it
resides in the process environment.
MBOX The name of the user's secondary mailbox file. A logical subset of
the special Filename transformations (also see folder) are sup-
ported. The default is ~/mbox. Traditionally this MBOX is used as
the file to save messages from the primary system mailbox that have
been read. Also see Message states.
NETRC
[v15-compat][Option] This variable overrides the default location
of the user's ~/.netrc file.
PAGER
Pathname of the program to use for backing the command more, and
when the crt variable enforces usage of a pager for output. The
default paginator is more(1) (path search through SHELL).
S-nail inspects the contents of this variable: if its contains the
string ``less'' then a non-existing environment variable LESS will
be set to (the portable) `RI', likewise for ``lv'' LV will option-
ally be set to `-c'. Also see colour-pager.
PATH A colon-separated list of directories that is searched by the shell
when looking for commands, for example
`/bin:/usr/bin:/usr/local/bin'.
POSIXLY_CORRECT
This environment entry is automatically squared with posix.
SHELL
The shell to use for the commands !, shell, the ~! COMMAND ESCAPES
and when starting subprocesses. A default shell is used if this
environment variable is not defined.
SOCKS5_PROXY
This environment entry is automatically squared with socks-proxy.
SOURCE_DATE_EPOCH
Specifies a time in seconds since the Unix epoch (1970-01-01) to be
used in place of the current time. This variable is looked up upon
program startup, and its existence will switch S-nail to a repro-
ducible mode (https://reproducible-builds.org) which uses determin-
istic random numbers, a special fixated pseudo LOGNAME and more.
This operation mode is used for development and by software pack-
agers. [v15 behaviour may differ] Currently an invalid setting is
only ignored, rather than causing a program abortion.
$ SOURCE_DATE_EPOCH=`date +%s` s-nail
TERM [Option] The terminal type for which output is to be prepared. For
extended colour and font control please refer to Coloured display,
and for terminal management in general to On terminal control and
line editor.
TMPDIR
Except for the root user this variable defines the directory for
temporary files to be used instead of /tmp (or the given compile-
time constant) if set, existent, accessible as well as read- and
writable. This variable is only used when it resides in the
process environment, but S-nail will ensure at startup that this
environment variable is updated to contain a usable temporary
directory.
USER Identical to LOGNAME (see there), but this variable is not stan-
dardized, should therefore not be used, and is only corrected if
already set.
VISUAL
Pathname of the text editor to use for the visual command and ~v
(see COMMAND ESCAPES); EDITOR is used for a less display oriented
editor.
FILES
~/.mailcap, /etc/mailcap
[Option] Personal and system-wide MIME type handler definition
files, see The Mailcap files. (The shown names are part of the RFC
1524 standard search path MAILCAPS.)
~/.mailrc, s-nail.rc
User-specific and system-wide files giving initial commands, the
Resource files. (The used filenames come from MAILRC and
system-mailrc, respectively.)
~/mbox
The default value for MBOX.
~/.mime.types, /etc/mime.types
Personal and system-wide MIME types, see The mime.types files.
~/.netrc
[v15-compat][Option] The default location of the user's .netrc file
- the section The .netrc file documents the file format. The used
path can be set via NETRC.
/dev/null
The data sink null(4).
~/.rnd
[Option] Possible location for persistent random entropy seed stor-
age, see tls-rand-file.
Resource files
Upon startup S-nail reads in several resource files, in order:
s-nail.rc
System wide initialization file (system-mailrc). Reading of this
file can be suppressed, either by using the -: (and according argu-
ment) or -n command line options, or by setting the ENVIRONMENT
variable MAILX_NO_SYSTEM_RC.
~/.mailrc
File giving initial commands. A different file can be chosen by
setting the ENVIRONMENT variable MAILRC. Reading of this file can
be suppressed with the -: command line option.
mailx-extra-rc
Defines a startup file to be read after all other resource files.
It can be used to specify settings that are not understood by other
mailx(1) implementations, for example.
The content of these files is interpreted as follows:
o The whitespace characters space, tabulator and newline, as well as
those defined by the variable ifs, are removed from the beginning and
end of input lines.
o Empty lines are ignored.
o Any other line is interpreted as a command. It may be spread over
multiple input lines if the newline character is ``escaped'' by plac-
ing a reverse solidus character `\' as the last character of the
line; whereas any leading whitespace of follow lines is ignored,
trailing whitespace before a escaped newline remains in the input.
o If the line (content) starts with the number sign `#' then it is a
comment-command and also ignored. (The comment-command is a real
command, which does nothing, and therefore the usual follow lines
mechanism applies!)
Errors while loading these files are subject to the settings of errexit
and posix. More files with syntactically equal content can be sourceed.
The following, saved in a file, would be an examplary content:
# This line is a comment command. And y\
es, it is really continued here.
set debug \
verbose
set editheaders
The mime.types files
As stated in HTML mail and MIME attachments S-nail needs to learn about
MIME (Multipurpose Internet Mail Extensions) media types in order to
classify message and attachment content. One source for them are
mime.types files, the loading of which can be controlled by setting the
variable mimetypes-load-control. Another is the command mimetype, which
also offers access to S-nails MIME type cache. mime.types files have the
following syntax:
type/subtype extension [extension ...]
# For example text/html html htm
where `type/subtype' define the MIME media type, as standardized in RFC
2046: `type' is used to declare the general type of data, while the
`subtype' specifies a specific format for that type of data. One or mul-
tiple filename `extension's, separated by whitespace, can be bound to the
media type format. Comments may be introduced anywhere on a line with a
number sign `#', causing the remaining line to be discarded. S-nail also
supports an extended, non-portable syntax in especially crafted files,
which can be loaded via the alternative value syntax of
mimetypes-load-control, and prepends an optional `type-marker':
[type-marker ]type/subtype extension [extension ...]
The following type markers are supported:
? Treat message parts with this content as plain text.
?t The same as plain ?.
?h Treat message parts with this content as HTML tagsoup. If the
[Option]al HTML-tagsoup-to-text converter is not available treat
the content as plain text instead.
?H Likewise ?h, but instead of falling back to plain text require an
explicit content handler to be defined.
?q If no handler can be found a text message is displayed which says
so. This can be annoying, for example signatures serve a contex-
tual purpose, their content is of no use by itself. This marker
will avoid displaying the text message.
Further reading: for sending messages: mimetype,
mime-allow-text-controls, mimetypes-load-control. For reading etc. mes-
sages: HTML mail and MIME attachments, The Mailcap files, mimetype,
mime-counter-evidence, mimetypes-load-control, pipe-TYPE/SUBTYPE,
pipe-EXTENSION.
The Mailcap files
[Option] RFC 1524 defines a ``User Agent Configuration Mechanism'' to be
used to inform mail user agent programs about the locally installed
facilities for handling various data formats, i.e., about commands and
how they can be used to display, edit et cetera MIME part contents, as
well as a default path search that includes multiple possible locations
of resource files, and the MAILCAPS environment variable to overwrite
that. Handlers found from doing the path search will be cached, the com-
mand mailcap operates on that cache, and the variable mailcap-disable
will suppress automatic loading, and usage of any mailcap handlers. HTML
mail and MIME attachments gives a general overview of how MIME types are
handled.
``Mailcap'' files consist of a set of newline separated entries. Comment
lines start with a number sign `#' (in the first column!) and are
ignored. Empty lines are ignored. All other lines are interpreted as
mailcap entries. An entry definition may be split over multiple lines by
placing the reverse solidus character `\' last in all but the final line.
The standard does not specify how leading whitespace of successive lines
is to be treated, therefore they are retained.
``Mailcap'' entries consist of a number of semicolon `;' separated
fields. The first two fields are mandatory and must occur in the speci-
fied order, the remaining fields are optional and may appear in any
order. Leading and trailing whitespace of field content is ignored
(removed). The reverse solidus `\' character can be used to escape any
following character including semicolon and itself in the content of the
second field, and in value parts of any optional key/value field.
The first field defines the MIME `TYPE/SUBTYPE' the entry is about to
handle (case-insensitively). If the subtype is specified as an asterisk
`*' the entry is meant to match all subtypes of the named type, e.g.,
`audio/*' would match any audio type. The second field is the view shell
command used to display MIME parts of the given type.
Data consuming shell commands will be fed message (MIME part) data on
standard input unless one or more instances of the (unquoted) string `%s'
are used: these formats will be replaced with a temporary file(name) that
has been prefilled with the parts data. Data producing shell commands
are expected to generata data on their standard output unless that format
is used. In all cases any given `%s' format is replaced with a properly
shell quoted filename. When a command requests a temporary file via `%s'
then that will be removed again, as if the x-mailx-tmpfile and
x-mailx-tmpfile-fill flags had been set; unless the command requests
x-mailx-async the x-mailx-tmpfile-unlink flag is also implied; see below
for more.
Optional fields define single-word flags (case-insensitive), or key /
value pairs consisting of a case-insensitive keyword, an equals sign `=',
and a shell command; whitespace surrounding the equals sign is removed.
Optional fields include the following:
compose
A program that can be used to compose a new body or body part in
the given format. (Currently unused.)
composetyped
Similar to the compose field, but is to be used when the composing
program needs to specify the `Content-type:' header field to be
applied to the composed data. (Currently unused.)
copiousoutput
A flag field which indicates that the output of the view command is
integrable into S-nails normal visual display. It is mutually
exclusive with needsterminal.
description
A textual description that describes this type of data. The text
may optionally be enclosed within double quotation marks `"'.
edit A program that can be used to edit a body or body part in the given
format. (Currently unused.)
nametemplate
This field specifies a filename format for the `%s' format used in
the shell command fields, in which `%s' will be replaced by a ran-
dom string. (The filename is also stored in and passed to subpro-
cesses via MAILX_FILENAME_TEMPORARY.) The standard says this is
``only expected to be relevant in environments where filename
extensions are meaningful'', and so this field is ignored unless
the `%s' is a prefix, optionally followed by (ASCII) alphabetic and
numeric characters, the underscore and the period. For example, to
specify that a JPG file is to be passed to an image viewer with a
name ending in `.jpg', `nametemplate=%s.jpg' can be used.
needsterminal
This flag field indicates that the given shell command must be run
on an interactive terminal. S-nail will temporarily release the
terminal to the given command in interactive mode, in non-interac-
tive mode this entry will be entirely ignored; this flag implies
x-mailx-noquote.
print
A program that can be used to print a message or body part in the
given format. (Currently unused.)
test Specifies a program to be run to test some condition, for example,
the machine architecture, or the window system in use, to determine
whether or not this mailcap entry applies. If the test fails, a
subsequent mailcap entry should be sought; also see
x-mailx-test-once. Standard I/O of the test program is redirected
from and to /dev/null, and the format `%s' is not supported (the
data does not yet exist).
textualnewlines
A flag field which indicates that this type of data is line-ori-
ented and that, if encoded in `base64', all newlines should be con-
verted to canonical form (CRLF) before encoding, and will be in
that form after decoding. (Currently unused.)
x11-bitmap
Names a file, in X11 bitmap (xbm) format, which points to an appro-
priate icon to be used to visually denote the presence of this kind
of data. This field is not used by S-nail.
x-mailx-async
Extension flag field that denotes that the given view command shall
be executed asynchronously, without blocking S-nail. Cannot be
used in conjunction with needsterminal; the standard output of the
command will go to /dev/null.
x-mailx-noquote
An extension flag field that indicates that even a copiousoutput
view command shall not be used when quoteing messages, as it would
by default.
x-mailx-test-once
Extension flag which denotes whether the given test command shall
be evaluated once only with its exit status being cached. This is
handy if some global unchanging condition is to be queried, like
``running under the X Window System''.
x-mailx-tmpfile
Extension flag field that requests creation of a zero-sized tempo-
rary file, the name of which is to be placed in the environment
variable MAILX_FILENAME_TEMPORARY. It is an error to use this flag
with commands that include a `%s' format (because that is imple-
mented by means of this temporary file).
x-mailx-tmpfile-fill
Normally the MIME part content is passed to the handler via stan-
dard input; if this flag is set then the data will instead be writ-
ten into the implied x-mailx-tmpfile. In order to cause deletion
of the temporary file you will have to set x-mailx-tmpfile-unlink
explicitly! It is an error to use this flag with commands that
include a `%s' format.
x-mailx-tmpfile-unlink
Extension flag field that requests that the temporary file shall be
deleted automatically when the command loop is entered again at
latest. It is an error to use this flag with commands that include
a `%s' format, or in conjunction with x-mailx-async.
x-mailx-tmpfile is implied.
x-mailx-last-resort
An extension flag that indicates that this handler shall only be
used as a last resort, when no other source (see HTML mail and MIME
attachments) provides a MIME handler.
x-mailx-ignore
An extension that enforces that this handler is not used at all.
The standard includes the possibility to define any number of additional
fields, prefixed by `x-'. Flag fields apply to the entire ``Mailcap''
entry -- in some unusual cases, this may not be desirable, but differen-
tiation can be accomplished via separate entries, taking advantage of the
fact that subsequent entries are searched if an earlier one does not pro-
vide enough information. For example, if a view command needs to specify
the needsterminal flag, but the compose command shall not, the following
will help out the latter:
application/postscript; ps-to-terminal %s; needsterminal
application/postscript; ps-to-terminal %s; compose=idraw %s
In value parts of command fields any occurrence of the format string `%t'
will be replaced by the `TYPE/SUBTYPE' specification. Any named parame-
ter from a messages' `Content-type:' field may be embedded into the com-
mand line using the format `%{' followed by the parameter name and a
closing brace `}' character. The entire parameter should appear as a
single command line argument, regardless of embedded spaces, shell quot-
ing will be performed by the RFC 1524 processor, thus:
# Message
Content-type: multipart/mixed; boundary=42
# Mailcap file
multipart/*; /usr/local/bin/showmulti \
%t %{boundary} ; composetyped = /usr/local/bin/makemulti
# Executed shell command
/usr/local/bin/showmulti multipart/mixed 42
Note that S-nail does not support handlers for multipart MIME parts as
shown in this example (as of today). It does not support the additional
formats `%n' and `%F'. An example file, also showing how to properly
deal with the expansion of `%s', which includes any quotes that are nec-
essary to make it a valid shell argument by itself and thus will cause
undesired behaviour when placed in additional user-provided quotes:
# Comment line
text/richtext; richtext %s; copiousoutput
text/x-perl; perl -cWT %s; nametemplate = %s.pl
# Exit EX_TEMPFAIL=75 on signal
application/pdf; \
infile=%s\; \
trap "rm -f ${infile}" EXIT\; \
trap "exit 75" INT QUIT TERM\; \
mupdf "${infile}"; \
test = [ -n "${DISPLAY}" ]; \
nametemplate = %s.pdf; x-mailx-async
application/pdf; pdftotext -layout - -; copiousoutput
application/*; echo "This is \\"%t\\" but \
is 50 \% Greek to me" \; < %s head -c 512 | cat -vet; \
copiousoutput; x-mailx-noquote; x-mailx-last-resort
Further reading: HTML mail and MIME attachments, The mime.types files,
mimetype, MAILCAPS, mime-counter-evidence, pipe-TYPE/SUBTYPE,
pipe-EXTENSION.
The .netrc file
User credentials for machine accounts (see On URL syntax and credential
lookup) can be placed in the .netrc file, which will be loaded and cached
when requested by netrc-lookup. The default location ~/.netrc may be
overridden by the NETRC environment variable. As long as syntax con-
straints are honoured the file source may be replaced with the output of
the shell command set in netrc-pipe, to load an encrypted file, for exam-
ple. The cache can be managed with the command netrc.
The file consists of space, tabulator or newline separated tokens. This
parser implements a superset of the original BSD syntax, but users should
nonetheless be aware of portability glitches, shall their .netrc be
usable across multiple programs and platforms:
o BSD only supports double quotation marks, for example `password "pass
with spaces"'.
o BSD (only?) supports escaping of single characters via a reverse
solidus (a space could be escaped via `\ '), in- as well as outside
of a quoted string. This method is assumed to be present, and will
actively be used to quote double quotation marks `"' and reverse
solidus `\' characters inside the login and password tokens, for
example for display purposes.
o BSD does not require a final quotation mark of the last user input
token.
o The original BSD (Berknet) parser also supported a format which
allowed tokens to be separated with commas - whereas at least
Hewlett-Packard still seems to support this syntax, this parser does
not!
o As a non-portable extension some widely-used programs support shell-
style comments: if an input line starts, after any amount of white-
space, with a number sign `#', then the rest of the line is ignored.
o Whereas other programs may require that the .netrc file is accessible
by only the user if it contains a password token for any other login
than ``anonymous'', this parser will always require these strict per-
missions.
Of the following list of supported tokens this parser uses (and caches)
machine, login and password. An existing default entry will not be used.
machine name
The hostname of the entries' machine, lowercase-normalized before
use. Any further file content, until either end-of-file or the
occurrence of another machine or a default first-class token is
bound (only related) to the machine name.
As an extension that should not be the cause of any worries this
parser supports a single wildcard prefix for name:
machine *.example.com login USER password PASS
machine pop3.example.com login USER password PASS
machine smtp.example.com login USER password PASS
which would match `xy.example.com' as well as `pop3.example.com',
but neither `example.com' nor `local.smtp.example.com'. In the
example neither `pop3.example.com' nor `smtp.example.com' will be
matched by the wildcard, since the exact matches take precedence
(it is however faster to specify it the other way around).
default
This is the same as machine except that it is a fallback entry that
is used shall none of the specified machines match; only one
default token may be specified, and it must be the last first-class
token.
login name
The user name on the remote machine.
password string
The user's password on the remote machine.
account string
Supply an additional account password. This is merely for FTP pur-
poses.
macdef name
Define a macro. A macro is defined with the specified name; it is
formed from all lines beginning with the next line and continuing
until a blank line is (consecutive newline characters are) encoun-
tered. (Note that macdef entries cannot be utilized by multiple
machines, too, but must be defined following the machine they are
intended to be used with.) If a macro named init exists, it is
automatically run as the last step of the login process. This is
merely for FTP purposes.
EXAMPLES
An example configuration
# This example assumes v15.0 compatibility mode
set v15-compat
# Request strict TLL transport layer security checks
set tls-verify=strict
# Where are the up-to-date TLS certificates?
# (Since we manage up-to-date ones explicitly, do not use any,
# possibly outdated, default certificates shipped with OpenSSL)
#set tls-ca-dir=/etc/ssl/certs
set tls-ca-file=/etc/ssl/certs/ca-certificates.crt
set tls-ca-no-defaults
#set tls-ca-flags=partial-chain
wysh set smime-ca-file="${tls-ca-file}" \
smime-ca-no-defaults #smime-ca-flags="${tls-ca-flags}"
# This could be outsourced to a central configuration file via
# tls-config-file plus tls-config-module if the used library allows.
# CipherString: explicitly define the list of ciphers, which may
# improve security, especially with protocols older than TLS v1.2.
# See ciphers(1). Possibly best to only use tls-config-pairs-HOST
# (or -USER@HOST), as necessary, again..
# Note that TLSv1.3 uses Ciphersuites= instead, which will join
# with CipherString (if protocols older than v1.3 are allowed)
# Curves: especially with TLSv1.3 curves selection may be desired.
# MinProtocol,MaxProtocol: do not use protocols older than TLS v1.2.
# Change this only when the remote server does not support it:
# maybe use chain support via tls-config-pairs-HOST / -USER@HOST
# to define such explicit exceptions, then, e.g.,
# MinProtocol=TLSv1.1
if "$tls-features" =% ,+ctx-set-maxmin-proto,
wysh set tls-config-pairs='\
CipherString=TLSv1.2:!aNULL:!eNULL:@STRENGTH,\
Curves=P-521:P-384:P-256,\
MinProtocol=TLSv1.1'
else
wysh set tls-config-pairs='\
CipherString=TLSv1.2:!aNULL:!eNULL:@STRENGTH,\
Curves=P-521:P-384:P-256,\
Protocol=-ALL\,+TLSv1.1 \, +TLSv1.2\, +TLSv1.3'
endif
# Essential setting: select allowed character sets
set sendcharsets=utf-8,iso-8859-1
# A very kind option: when replying to a message, first try to
# use the same encoding that the original poster used herself!
set reply-in-same-charset
# When replying, do not merge From: and To: of the original message
# into To:. Instead old From: -> new To:, old To: -> merge Cc:.
set recipients-in-cc
# When sending messages, wait until the Mail-Transfer-Agent finishs.
# Only like this you will be able to see errors reported through the
# exit status of the MTA (including the built-in SMTP one)!
set sendwait
# Only use built-in MIME types, no mime.types(5) files
set mimetypes-load-control
# Default directory where we act in (relative to $HOME)
set folder=mail
# A leading "+" (often) means: under *folder*
# *record* is used to save copies of sent messages
set MBOX=+mbox.mbox DEAD=+dead.txt \
record=+sent.mbox record-files record-resent
# Make "file mymbox" and "file myrec" go to..
shortcut mymbox %:+mbox.mbox myrec +sent.mbox
# Not really optional, e.g., for S/MIME
set from='Your Name <address AT exam.ple>'
# It may be necessary to set hostname and/or smtp-hostname
# if the "SERVER" of mta and "domain" of from do not match.
# The `urlencode' command can be used to encode USER and PASS
set mta=(smtps?|submissions?)://[USER[:PASS]@]SERVER[:PORT] \
smtp-auth=login/plain... \
smtp-use-starttls
# Never refuse to start into interactive mode, and more
set emptystart \
colour-pager crt= \
followup-to followup-to-honour=ask-yes fullnames \
history-file=+.s-nailhist history-size=-1 history-gabby \
mime-counter-evidence=0b1111 \
prompt='?\$?!\$!/\$^ERRNAME[\$account#\$mailbox-display]? ' \
reply-to-honour=ask-yes \
umask=
# Only include the selected header fields when typing messages
headerpick type retain from_ date from to cc subject \
message-id mail-followup-to reply-to
# ...when forwarding messages
headerpick forward retain subject date from to cc
# ...when saving message, etc.
#headerpick save ignore ^Original-.*$ ^X-.*$
# Some mailing lists
mlist '@xyz-editor\.xyz$' '@xyzf\.xyz$'
mlsubscribe '^xfans@xfans\.xyz$'
# Handle a few file extensions (to store MBOX databases)
filetype bz2 'bzip2 -dc' 'bzip2 -zc' \
gz 'gzip -dc' 'gzip -c' xz 'xz -dc' 'xz -zc' \
zst 'zstd -dc' 'zstd -19 -zc' \
zst.pgp 'gpg -d | zstd -dc' 'zstd -19 -zc | gpg -e'
# A real life example of a very huge free mail provider
# Instead of directly placing content inside `account',
# we `define' a macro: like that we can switch "accounts"
# from within *on-compose-splice*, for example!
define XooglX {
set folder=~/spool/XooglX inbox=+syste.mbox sent=+sent
set from='Your Name <address AT examp.ple>'
set pop3-no-apop-pop.gmXil.com
shortcut pop %:pop3s://pop.gmXil.com
shortcut imap %:imaps://imap.gmXil.com
# Or, entirely IMAP based setup
#set folder=imaps://imap.gmail.com record="+[Gmail]/Sent Mail" \
# imap-cache=~/spool/cache
set mta=smtp://USER:PASS AT smtp.com smtp-use-starttls
# Alternatively:
set mta=smtps://USER:PASS AT smtp.com:465
}
account XooglX {
\call XooglX
}
# Here is a pretty large one which does not allow sending mails
# if there is a domain name mismatch on the SMTP protocol level,
# which would bite us if the value of from does not match, e.g.,
# for people who have a sXXXXeforge project and want to speak
# with the mailing list under their project account (in from),
# still sending the message through their normal mail provider
define XandeX {
set folder=~/spool/XandeX inbox=+syste.mbox sent=+sent
set from='Your Name <address AT exam.ple>'
shortcut pop %:pop3s://pop.yaXXex.com
shortcut imap %:imaps://imap.yaXXex.com
set mta=smtps://USER:PASS AT smtp.com:465 \
hostname=yaXXex.com smtp-hostname=
}
account XandeX {
\call Xandex
}
# Create some new commands so that, e.g., `ls /tmp' will..
commandalias lls '!ls ${LS_COLOUR_FLAG} -aFlrS'
commandalias llS '!ls ${LS_COLOUR_FLAG} -aFlS'
set pipe-message/external-body='?* echo $MAILX_EXTERNAL_BODY_URL'
# We do not support gpg(1) directly yet. But simple --clearsign'd
# message parts can be dealt with as follows:
define V {
localopts yes
wysh set pipe-text/plain=$'?*#++=?\
< "${MAILX_FILENAME_TEMPORARY}" awk \
-v TMPFILE="${MAILX_FILENAME_TEMPORARY}" \'\
BEGIN{done=0}\
/^-----BEGIN PGP SIGNED MESSAGE-----/,/^$/ {\
if(done++ != 0)\
next;\
print "--- GPG --verify ---";\
system("gpg --verify " TMPFILE " 2>&1");\
print "--- GPG --verify ---";\
print "";\
next;\
}\
/^-----BEGIN PGP SIGNATURE-----/,\
/^-----END PGP SIGNATURE-----/{\
next;\
}\
{print}\
\''
print
}
commandalias V '\'call V
When storing passwords in ~/.mailrc appropriate permissions should be set
on this file with `$ chmod 0600 ~/.mailrc'. If the [Option]al
netrc-lookup is available user credentials can be stored in the central
~/.netrc file instead; e.g., here is a different version of the example
account that sets up SMTP and POP3:
define XandeX {
set folder=~/spool/XandeX inbox=+syste.mbox sent=+sent
set from='Your Name <address AT exam.ple>'
set netrc-lookup
# Load an encrypted ~/.netrc by uncommenting the next line
#set netrc-pipe='gpg -qd ~/.netrc.pgp'
set mta=smtps://smtp.yXXXXx.ru:465 \
smtp-hostname= hostname=yXXXXx.com
set pop3-keepalive=240 pop3-no-apop-pop.yXXXXx.ru
commandalias xp fi pop3s://pop.yXXXXx.ru
}
account XandeX {
\call XandeX
}
and, in the ~/.netrc file:
machine *.yXXXXx.ru login USER password PASS
This configuration should now work just fine:
$ echo text | s-nail -dvv -AXandeX -s Subject user AT exam.ple
S/MIME step by step
[Option] The first thing that is needed for Signed and encrypted messages
with S/MIME is a personal certificate, and a private key. The certifi-
cate contains public information, in particular a name and email
address(es), and the public key that can be used by others to encrypt
messages for the certificate holder (the owner of the private key), and
to verify signed messages generated with that certificate('s private
key). Whereas the certificate is included in each signed message, the
private key must be kept secret. It is used to decrypt messages that
were previously encrypted with the public key, and to sign messages.
For personal use it is recommended to get a S/MIME certificate from one
of the major CAs on the Internet. Many CAs offer such certificates for
free. Usually offered is a combined certificate and private key in
PKCS#12 format which S-nail does not accept directly. To convert it to
PEM format, the following shell command can be used; please read on for
how to use these PEM files.
$ openssl pkcs12 -in cert.p12 -out certpem.pem -clcerts -nodes
$ # Alternatively
$ openssl pkcs12 -in cert.p12 -out cert.pem -clcerts -nokeys
$ openssl pkcs12 -in cert.p12 -out key.pem -nocerts -nodes
There is also https://www.CAcert.org which issues client and server cer-
tificates to members of their community for free; their root certificate
(https://www.cacert.org/certs/root.crt) is often not in the default set
of trusted CA root certificates, though, which means their root certifi-
cate has to be downloaded separately, and needs to be part of the S/MIME
certificate validation chain by including it in smime-ca-dir or as a
vivid member of the smime-ca-file. But let us take a step-by-step tour
on how to setup S/MIME with a certificate from CAcert.org despite this
situation!
First of all you will have to become a member of the CAcert.org commu-
nity, simply by registrating yourself via the web interface. Once you
are, create and verify all email addresses you want to be able to create
signed and encrypted messages for/with using the corresponding entries of
the web interface. Now ready to create S/MIME certificates, so let us
create a new ``client certificate'', ensure to include all email
addresses that should be covered by the certificate in the following web
form, and also to use your name as the ``common name''.
Create a private key and a certificate request on your local computer
(please see the manual pages of the used commands for more in-depth
knowledge on what the used arguments etc. do):
$ openssl req -nodes -newkey rsa:4096 -keyout key.pem -out creq.pem
Afterwards copy-and-paste the content of ``creq.pem'' into the certifi-
cate-request (CSR) field of the web form on the CAcert.org website (you
may need to unfold some ``advanced options'' to see the corresponding
text field). This last step will ensure that your private key (which
never left your box) and the certificate belong together (through the
public key that will find its way into the certificate via the certifi-
cate-request). You are now ready and can create your CAcert certified
certificate. Download and store or copy-and-paste it as ``pub.crt''.
Yay. In order to use your new S/MIME setup a combined private key/public
key (certificate) file has to be created:
$ cat key.pem pub.crt > ME AT HERE.paired
This is the file S-nail will work with. If you have created your private
key with a passphrase then S-nail will ask you for it whenever a message
is signed or decrypted, unless this operation has been automated as
described in Signed and encrypted messages with S/MIME. Set the follow-
ing variables to henceforth use S/MIME (setting smime-ca-file is of
interest for verification only):
? set smime-ca-file=ALL-TRUSTED-ROOT-CERTS-HERE \
smime-sign-cert=ME AT HERE.paired \
smime-sign-digest=SHA512 \
smime-sign from=myname AT my.host
Using CRLs with S/MIME or TLS
[Option] Certification authorities (CAs) issue certificate revocation
lists (CRLs) on a regular basis. These lists contain the serial numbers
of certificates that have been declared invalid after they have been
issued. Such usually happens because the private key for the certificate
has been compromised, because the owner of the certificate has left the
organization that is mentioned in the certificate, etc. To seriously use
S/MIME or TLS verification, an up-to-date CRL is required for each
trusted CA. There is otherwise no method to distinguish between valid
and invalidated certificates. S-nail currently offers no mechanism to
fetch CRLs, nor to access them on the Internet, so they have to be
retrieved by some external mechanism.
S-nail accepts CRLs in PEM format only; CRLs in DER format must be con-
verted, like, e.g.:
$ openssl crl -inform DER -in crl.der -out crl.pem
To tell S-nail about the CRLs, a directory that contains all CRL files
(and no other files) must be created. The smime-crl-dir or tls-crl-dir
variables, respectively, must then be set to point to that directory.
After that, S-nail requires a CRL to be present for each CA that is used
to verify a certificate.
FAQ
In general it is a good idea to turn on debug (-d) and / or verbose (-v,
twice) if something does not work well. Very often a diagnostic message
can be produced that leads to the problems' solution.
S-nail shortly hangs on startup
This can have two reasons, one is the necessity to wait for a file lock
and cannot be helped, the other being that S-nail calls the function
uname(2) in order to query the nodename of the box (sometimes the real
one is needed instead of the one represented by the internal variable
hostname). One may have varying success by ensuring that the real host-
name and `localhost' have entries in /etc/hosts, or, more generally, that
the name service is properly setup - and does hostname(1) return the
expected value? Does this local hostname have a domain suffix? RFC 6762
standardized the link-local top-level domain `.local', try again after
adding an (additional) entry with this extension.
I cannot login to Google mail (via OAuth)
Since 2014 some free service providers classify programs as ``less
secure'' unless they use a special authentication method (OAuth 2.0)
which was not standardized for non-HTTP protocol authentication token
query until August 2015 (RFC 7628).
Different to Kerberos / GSSAPI, which is developed since the mid of the
1980s, where a user can easily create a local authentication ticket for
her- and himself with the locally installed kinit(1) program, that proto-
col has no such local part but instead requires a world-wide-web query to
create or fetch a token; since there is no local cache this query would
have to be performed whenever S-nail is invoked (in interactive sessions
situation may differ).
S-nail does not directly support OAuth. It, however, supports XOAUTH2 /
OAUTHBEARER, see But, how about XOAUTH2 / OAUTHBEARER? If that is not
used it is necessary to declare S-nail a ``less secure app'' (on the
providers account web page) in order to read and send mail. However, it
also seems possible to take the following steps instead:
1. give the provider the number of a mobile phone,
2. enable ``2-Step Verification'',
3. create an application specific password (16 characters), and
4. use that special password instead of the real Google account pass-
word in S-nail (for more on that see the section On URL syntax and
credential lookup).
But, how about XOAUTH2 / OAUTHBEARER?
Following up I cannot login to Google mail (via OAuth) one OAuth-based
authentication method is available: the OAuth 2.0 bearer token usage as
standardized in RFC 6750 (according SASL mechanism in RFC 7628), also
known as XOAUTH2 and OAUTHBEARER, allows fetching a temporary access
token via the web that can locally be used as a password. The protocol
is simple and extendable, token updates or even password changes via a
simple TLS secured server login would be possible in theory, but today a
web browser and an external support tool are prerequisites for using this
authentication method. The token times out and must be periodically
refreshed via the web.
Some hurdles must be taken before being able to use this method. Using
GMail as an example, an application (that is a name) must be registered,
for which credentials, a ``client ID'' and a ``client secret'', need to
be created and saved locally (in a secure way). These initial configura-
tion steps can be performed at
https://console.developers.google.com/apis/credentials.
Thereafter a refresh token can be requested; a python program to do this
for GMail accounts is
https://github.com/google/gmail-oauth2-tools/raw/master/python/
oauth2.py:
$ python oauth2.py --user=EMAIL \
--client-id=THE-ID --client-secret=THE-SECRET \
--generate_oauth2_token
To authorize token, visit this url and follow the directions:
https://accounts.google.com/o/oauth2/auth?client_id=...
Enter verification code: ...
Refresh Token: ...
Access Token: ...
Access Token Expiration Seconds: 3600
$ # Of which the last three are actual token responses.
$ # Thereafter access tokens can regularly be refreshed
$ # via the created refresh token (read on)
The generated refresh token must also be saved locally (securely). The
procedure as a whole can be read at
https://github.com/google/gmail-oauth2-tools/wiki/
OAuth2DotPyRunThrough.
Since periodic timers are not yet supported, keeping an access token up-
to-date (from within S-nail) can only be performed via the hook
on-main-loop-tick, or (for sending only) on-compose-enter (for more on
authentication please see the section On URL syntax and credential
lookup):
set on-main-loop-tick=o-m-l-t on-compose-enter=o-c-e
define o-m-l-t {
xcall update_access_token
}
define o-c-e {
xcall update_access_token
}
set access_token_=0
define update_access_token {
local set i epoch_sec epoch_nsec
vput vexpr i epoch
eval set $i # set epoch_sec/_nsec of vexpr epoch
vput vexpr i + $access_token_ 2100
if $epoch_sec -ge $i
vput ! password python oauth2.py --user=EMAIL \
--client-id=THE-ID --client-secret=THE-SECRET \
--refresh-token=THE-REFRESH-TOKEN |\
sed '1b PASS;d; :PASS s/^.\{1,\}:\(.\{1,\}\)$/\1/'
vput csop password trim "$password"
if -n "$verbose"
echo password is <$password>
endif
set access_token_=$epoch_sec
endif
}
Not "defunctional", but the editor key does not work
Two thinkable situations: the first is a shadowed sequence; setting
debug, or the most possible verbose mode, causes a printout of the bind
tree after that is built; being a cache, this happens only upon startup
or after modifying bindings.
Or second, terminal libraries (see On terminal control and line editor,
bind, termcap) may report different codes than the terminal really sends,
rendering bindings dysfunctional because expected and received data do
not match; the verbose listing of bindings will show the byte sequences
that are expected. (One common source of problems is that the -- possi-
bly even non-existing -- keypad is not turned on, and the resulting lay-
out reports the keypad control codes for the normal keyboard keys.)
To overcome the situation use for example the program cat(1) with its
option -v, if available, to see the byte sequences which are actually
produced by keypresses, and use the variable termcap to make S-nail aware
of them. The terminal this is typed on produces some unexpected
sequences, here for an example the shifted home key:
? set verbose
? bind*
# 1B 5B=[ 31=1 3B=; 32=2 48=H
bind base :kHOM z0
? x
$ cat -v
^[[H
$ s-nail -v -Stermcap='kHOM=\E[H'
? bind*
# 1B 5B=[ 48=H
bind base :kHOM z0
Can S-nail git-send-email?
Yes. Put (at least parts of) the following in your ~/.gitconfig:
[sendemail]
smtpserver = /usr/bin/s-nail
smtpserveroption = -t
#smtpserveroption = -Sexpandaddr
smtpserveroption = -Athe-account-you-need
##
suppresscc = all
suppressfrom = false
assume8bitEncoding = UTF-8
#to = /tmp/OUT
confirm = always
chainreplyto = true
multiedit = false
thread = true
quiet = true
annotate = true
Newer git(1) versions (v2.33.0) added the option sendmailCmd. Patches
can also be send directly, for example:
$ git format-patch -M --stdout HEAD^ |
s-nail -A the-account-you-need -t RECEIVER
Howto handle stale dotlock files
folder sometimes fails to open MBOX mail databases because creation of
dotlock files is impossible due to existing but unowned lock files.
S-nail does not offer an option to deal with those files, because it is
considered a site policy what counts as unowned, and what not. The site
policy is usually defined by administrator(s), and expressed in the con-
figuration of a locally installed MTA (for example Postfix
`stale_lock_time=500s'). Therefore the suggestion:
$ </dev/null s-nail -s 'MTA: be no frog, handle lock' $LOGNAME
By sending a mail to yourself the local MTA can use its normal queue
mechanism to try the delivery multiple times, finally decide a lock file
has become stale, and remove it.
IMAP CLIENT
[Option]ally there is IMAP client support available. This part of the
program is obsolete and will vanish in v15 with the large MIME and I/O
layer rewrite, because it uses old-style blocking I/O and makes excessive
use of signal based long code jumps. Support can hopefully be readded
later based on a new-style I/O, with SysV signal handling. In fact the
IMAP support had already been removed from the codebase, but was rein-
stantiated on user demand: in effect the IMAP code is at the level of
S-nail v14.8.16 (with imapcodec being the sole exception), and should be
treated with some care.
IMAP uses the `imap://' and `imaps://' protocol prefixes, and an IMAP-
based folder may be used. IMAP URLs (paths) undergo inspections and pos-
sible transformations before use (and the command imapcodec can be used
to manually apply them to any given argument). Hierarchy delimiters are
normalized, a step which is configurable via the imap-delim variable
chain, but defaults to the first seen delimiter otherwise. S-nail sup-
ports internationalised IMAP names, and en- and decodes the names from
and to the ttycharset as necessary and possible. If a mailbox name is
expanded (see Filename transformations) to an IMAP mailbox, all names
that begin with `+' then refer to IMAP mailboxes below the folder target
box, while folder names prefixed by `@' refer to folders below the hier-
archy base, so the following will list all folders below the current one
when in an IMAP mailbox: `folders @'.
Note: some IMAP servers do not accept the creation of mailboxes in the
hierarchy base, but require that they are created as subfolders of
`INBOX' - with such servers a folder name of the form
imaps://mylogin AT imap.example/INBOX.
should be used (the last character is the server's hierarchy delimiter).
The following IMAP-specific commands exist:
cache
Only applicable to cached IMAP mailboxes; takes a message list and
reads the specified messages into the IMAP cache.
connect
If operating in disconnected mode on an IMAP mailbox, switch to
online mode and connect to the mail server while retaining the
mailbox status. See the description of the disconnected variable
for more information.
disconnect
If operating in online mode on an IMAP mailbox, switch to discon-
nected mode while retaining the mailbox status. See the descrip-
tion of the disconnected variable for more. A list of messages may
optionally be given as argument; the respective messages are then
read into the cache before the connection is closed, thus `disco *'
makes the entire mailbox available for disconnected use.
imap Sends command strings directly to the current IMAP server. S-nail
operates always in IMAP `selected state' on the current mailbox;
commands that change this will produce undesirable results and
should be avoided. Useful IMAP commands are:
create Takes the name of an IMAP mailbox as an argu-
ment and creates it.
getquotaroot (RFC 2087) Takes the name of an IMAP mailbox
as an argument and prints the quotas that
apply to the mailbox. Not all IMAP servers
support this command.
namespace (RFC 2342) Takes no arguments and prints the
Personal Namespaces, the Other User's Names-
paces and the Shared Namespaces. Each names-
pace type is printed in parentheses; if there
are multiple namespaces of the same type,
inner parentheses separate them. For each
namespace a prefix and a hierarchy separator
is listed. Not all IMAP servers support this
command.
imapcodec
Perform IMAP path transformations. Supports vput (see Command
modifiers), and manages the error number !. The first argument
specifies the operation: e[ncode] normalizes hierarchy delimiters
(see imap-delim) and converts the strings from the locale
ttycharset to the internationalized variant used by IMAP, d[ecode]
performs the reverse operation. Encoding will honour the (global)
value of imap-delim.
The following IMAP-specific internal variables exist:
disconnected
(Boolean) When an IMAP mailbox is selected and this variable is
set, no connection to the server is initiated. Instead, data is
obtained from the local cache (see imap-cache). Mailboxes that are
not present in the cache and messages that have not yet entirely
been fetched from the server are not available; to fetch all mes-
sages in a mailbox at once, the command `copy * /dev/null' can be
used while still in connected mode. Changes that are made to IMAP
mailboxes in disconnected mode are queued and committed later when
a connection to that server is made. This procedure is not com-
pletely reliable since it cannot be guaranteed that the IMAP unique
identifiers (UIDs) on the server still match the ones in the cache
at that time. Data is saved to DEAD when this problem occurs.
disconnected-USER@HOST
The specified account is handled as described for the disconnected
variable above, but other accounts are not affected.
imap-auth-USER@HOST, imap-auth
Sets the IMAP authentication method. Supported are the default
`login', [v15-compat] `oauthbearer' (see FAQ entry But, how about
XOAUTH2 / OAUTHBEARER?), [v15-compat] `external' and `externanon'
(for TLS secured connections which pass a client certificate via
tls-config-pairs), as well as the [Option]al `cram-md5' and
`gssapi'. All methods need a user and a password except `gssapi'
and `external', which only need the former. `externanon' solely
builds upon the credentials passed via a client certificate, and is
usually the way to go since tested servers do not actually follow
RFC 4422, and fail if additional credentials are actually passed.
imap-cache
Enables caching of IMAP mailboxes. The value of this variable must
point to a directory that is either existent or can be created by
S-nail. All contents of the cache can be deleted by S-nail at any
time; it is not safe to make assumptions about them.
imap-delim-USER@HOST, imap-delim-HOST, imap-delim
The hierarchy separator used by the IMAP server. Whenever an IMAP
path is specified it will undergo normalization. One of the nor-
malization steps is the squeezing and adjustment of hierarchy sepa-
rators. If this variable is set, any occurrence of any character
of the given value that exists in the path will be replaced by the
first member of the value; an empty value will cause the default to
be used, it is `/.'. If not set, we will reuse the first hierarchy
separator character that is discovered in a user-given mailbox
name.
imap-keepalive-USER@HOST, imap-keepalive-HOST, imap-keepalive
IMAP servers may close the connection after a period of inactivity;
the standard requires this to be at least 30 minutes, but practical
experience may vary. Setting this variable to a numeric `value'
greater than 0 causes a `NOOP' command to be sent each `value' sec-
onds if no other operation is performed.
imap-list-depth
When retrieving the list of folders on an IMAP server, the folders
command stops after it has reached a certain depth to avoid possi-
ble infinite loops. The value of this variable sets the maximum
depth allowed. The default is 2. If the folder separator on the
current IMAP server is a slash `/', this variable has no effect and
the folders command does not descend to subfolders.
imap-use-starttls-USER@HOST, imap-use-starttls-HOST, imap-use-starttls
Causes S-nail to issue a `STARTTLS' command to make an unencrypted
IMAP session TLS encrypted. This functionality is not supported by
all servers, and is not used if the session is already encrypted by
the IMAPS method.
SEE ALSO
bogofilter(1), gpg(1), more(1), newaliases(1), openssl(1), sendmail(1),
sh(1), spamassassin(1), iconv(3), setlocale(3), aliases(5), termcap(5),
terminfo(5), locale(7), mailaddr(7), re_format(7) (or regex(7)),
mailwrapper(8), sendmail(8)
HISTORY
M. Douglas McIlroy writes in his article ``A Research UNIX Reader:
Annotated Excerpts from the Programmer's Manual, 1971-1986'' that a
mail(1) command already appeared in First Edition UNIX in 1971:
Electronic mail was there from the start. Never satisfied with its
exact behavior, everybody touched it at one time or another: to
assure the safety of simultaneous access, to improve privacy, to
survive crashes, to exploit uucp, to screen out foreign free-
loaders, or whatever. Not until v7 did the interface change
(Thompson). Later, as mail became global in its reach, Dave Pre-
sotto took charge and brought order to communications with a grab-
bag of external networks (v8).
BSD Mail, in large parts compatible with UNIX mail, was written in 1978
by Kurt Shoens and developed as part of the BSD UNIX distribution until
1995. This manual page is derived from ``The Mail Reference Manual''
that Kurt Shoens wrote for Mail 1.3, included in 3BSD in 1980. The com-
mon UNIX and BSD denominator became standardized as mailx(1) in the
X/Open Portability Guide Issue 2 (January 1987). After the rise of Open
Source BSD variants Mail saw continuous development in the individual
code forks, noticeably by Christos Zoulas in NetBSD. Based upon this
Nail, later Heirloom Mailx, was developed by Gunnar Ritter in the years
2000 until 2008. Since 2012 S-nail is maintained by Steffen Nurpmeso.
Electronic mail exchange in general is a concept even older. The earli-
est well documented electronic mail system was part of the Compatible
Time Sharing System (CTSS) at MIT, its MAIL command had been proposed in
a staff planning memo at the end of 1964 and was implemented in mid-1965
when Tom Van Vleck and Noel Morris wrote the necessary code. Similar
communication programs were built for other timesharing systems. One of
the most ambitious and influential was Murray Turoff's EMISARI. Created
in 1971 for the United States Office of Emergency Preparedness, EMISARI
combined private electronic messages with a chat system, public postings,
voting, and a user directory.
During the 1960s it was common to connect a large number of terminals to
a single, central computer. Connecting two computers together was rela-
tively unusual. This began to change with the development of the
ARPANET, the ancestor of today's Internet. In 1971 Ray Tomlinson adapted
the SNDMSG program, originally developed for the University of California
at Berkeley timesharing system, to give it the ability to transmit a mes-
sage across the network into the mailbox of a user on a different com-
puter. For the first time it was necessary to specify the recipient's
computer as well as an account name. Tomlinson decided that the under-
used commercial at `@' would work to separate the two.
Sending a message across the network was originally treated as a special
instance of transmitting a file, and so a MAIL command was included in
RFC 385 on file transfer in 1972. Because it was not always clear when
or where a message had come from, RFC 561 in 1973 aimed to formalize
electronic mail headers, including ``from'', ``date'', and ``subject''.
In 1975 RFC 680 described fields to help with the transmission of mes-
sages to multiple users, including ``to'', ``cc'', and ``bcc''. In 1977
these features and others went from best practices to a binding standard
in RFC 733. Queen Elizabeth II of England became the first head of state
to send electronic mail on March 26 1976 while ceremonially opening a
building in the British Royal Signals and Radar Establishment (RSRE) in
Malvern.
AUTHORS
Kurt Shoens, Edward Wang, Keith Bostic, Christos Zoulas, Gunnar Ritter.
S-nail is developed by Steffen Nurpmeso <s-mailx AT lists.eu>.
CAVEATS
[v15 behaviour may differ] Interrupting an operation via SIGINT aka
`control-C' from anywhere else but a command prompt is very problematic
and likely to leave the program in an undefined state: many library func-
tions cannot deal with the siglongjmp(3) that this software (still) per-
forms; even though efforts have been taken to address this, no sooner but
in v15 it will have been worked out: interruptions have not been disabled
in order to allow forceful breakage of hanging network connections, for
example (all this is unrelated to ignore).
The SMTP and POP3 protocol support of S-nail is very basic. Also, if it
fails to contact its upstream SMTP server, it will not make further
attempts to transfer the message at a later time (setting save and
sendwait may be useful). If this is a concern, it might be better to set
up a local SMTP server that is capable of message queuing.
BUGS
When a network-based mailbox is open, directly changing to another net-
work-based mailbox of a different protocol (i.e., from POP3 to IMAP or
vice versa) will cause a ``deadlock''.
After deleting some message of a POP3 mailbox the header summary falsely
claims that there are no messages to display, one needs to perform a
scroll or dot movement to restore proper state.
In `thread'ed sort mode a power user may encounter crashes very occasion-
ally (this is may and very).
Please report bugs to the contact-mail address, for example from within
s-nail: `? eval mail $contact-mail'. Including the verbose output of the
command version may be helpful:
? wysh set escape=! verbose; vput version xy; unset verbose;\
eval mail $contact-mail
Bug subject
!I xy
!.
Information on the web at `$ s-nail -X 'echo $contact-web; x''.
BSD November 11, 2021 BSD
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