WHO(1P) - phpMan

WHO(1P)                    POSIX Programmer's Manual                   WHO(1P)
PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       who -- display who is on the system
SYNOPSIS
       who [-mTu] [-abdHlprt] [file]
       who [-mu] -s [-bHlprt] [file]
       who -q [file]
       who am i
       who am I
DESCRIPTION
       The who utility shall list various pieces of information about accessi-
       ble users. The domain of accessibility is implementation-defined.
       Based on the options given, who can also list the user's name, terminal
       line, login time, elapsed time since activity occurred on the line, and
       the process ID of the command interpreter for each current system user.
OPTIONS
       The  who  utility  shall  conform  to  the  Base  Definitions volume of
       POSIX.1-2008, Section 12.2, Utility Syntax Guidelines.
       The following options shall be supported. The  metavariables,  such  as
       <line>, refer to fields described in the STDOUT section.
       -a        Process  the  implementation-defined  database  or named file
                 with the -b, -d, -l, -p, -r, -t, -T and -u options turned on.
       -b        Write the time and date of the last system reboot. The system
                 reboot  time  is the time at which the implementation is able
                 to commence running processes.
       -d        Write a list of all processes that have expired and not  been
                 respawned  by the init system process. The <exit> field shall
                 appear for dead processes and  contain  the  termination  and
                 exit values of the dead process. This can be useful in deter-
                 mining why a process terminated.
       -H        Write column headings above the regular output.
       -l        (The letter ell.) List only those lines on which  the  system
                 is  waiting  for  someone to login. The <name> field shall be
                 LOGIN in such cases. Other fields shall be the  same  as  for
                 user entries except that the <state> field does not exist.
       -m        Output only information about the current terminal.
       -p        List  any other process that is currently active and has been
                 previously spawned by init.
       -q        (Quick.) List only the names and the  number  of  users  cur-
                 rently logged on. When this option is used, all other options
                 shall be ignored.
       -r        Write the current run-level of the init process.
       -s        List only the <name>, <line>, and <time> fields.  This is the
                 default case.
       -t        Indicate the last change to the system clock.
       -T        Show  the  state of each terminal, as described in the STDOUT
                 section.
       -u        Write ``idle time'' for each displayed user  in  addition  to
                 any  other  information.  The idle time is the time since any
                 activity occurred on  the  user's  terminal.  The  method  of
                 determining this is unspecified.  This option shall list only
                 those users who are currently logged in.  The <name>  is  the
                 user's  login  name.  The  <line>  is the name of the line as
                 found in the directory /dev.  The <time> is the time that the
                 user  logged  in.  The  <activity> is the number of hours and
                 minutes since activity last occurred on that particular line.
                 A  dot  indicates  that the terminal has seen activity in the
                 last minute  and  is  therefore  ``current''.  If  more  than
                 twenty-four  hours have elapsed or the line has not been used
                 since boot time, the entry shall be marked <old>. This  field
                 is  useful when trying to determine whether a person is work-
                 ing at the terminal or not. The <pid> is the  process  ID  of
                 the user's login process.
OPERANDS
       The following operands shall be supported:
       am i, am I
                 In  the  POSIX  locale,  limit  the  output to describing the
                 invoking user, equivalent to the -m option. The am and i or I
                 must be separate arguments.
       file      Specify  a pathname of a file to substitute for the implemen-
                 tation-defined database of logged-on users that who  uses  by
                 default.
STDIN
       Not used.
INPUT FILES
       None.
ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of who:
       LANG      Provide  a  default  value for the internationalization vari-
                 ables that are unset or null. (See the Base Definitions  vol-
                 ume  of POSIX.1-2008, Section 8.2, Internationalization Vari-
                 ables for the precedence  of  internationalization  variables
                 used to determine the values of locale categories.)
       LC_ALL    If  set  to  a non-empty string value, override the values of
                 all the other internationalization variables.
       LC_CTYPE  Determine the locale for the interpretation of  sequences  of
                 bytes of text data as characters (for example, single-byte as
                 opposed to multi-byte characters in arguments).
       LC_MESSAGES
                 Determine the locale that should be used to affect the format
                 and  contents  of  diagnostic  messages  written  to standard
                 error.
       LC_TIME   Determine the locale used for the format and contents of  the
                 date and time strings.
       NLSPATH   Determine the location of message catalogs for the processing
                 of LC_MESSAGES.
       TZ        Determine the timezone used when writing date and time infor-
                 mation.  If TZ is unset or null, an unspecified default time-
                 zone shall be used.
ASYNCHRONOUS EVENTS
       Default.
STDOUT
       The who utility shall write its default format to the  standard  output
       in an implementation-defined format, subject only to the requirement of
       containing the information described above.
       XSI-conformant systems shall write the default information to the stan-
       dard output in the following general format:
           <name>[<state>]<line><time>[<activity>][<pid>][<comment>][<exit>]
       For the -b option, <line> shall be "systemboot".  The <name> is unspec-
       ified.
       The following format shall be used for the -T option:
           "%s %c %s %s\n" <name>, <terminal state>, <terminal name>,
               <time of login>
       where <terminal state> is one of the following characters:
       +       The terminal allows write access to other users.
       -       The terminal denies write access to other users.
       ?       The terminal write-access state cannot be determined.
       <space> This entry is not associated with a terminal.
       In the POSIX locale, the <time of login> shall be equivalent in  format
       to the output of:
           date +"%b %e %H:%M"
       If  the  -u option is used with -T, the idle time shall be added to the
       end of the previous format in an unspecified format.
STDERR
       The standard error shall be used only for diagnostic messages.
OUTPUT FILES
       None.
EXTENDED DESCRIPTION
       None.
EXIT STATUS
       The following exit values shall be returned:
        0    Successful completion.
       >0    An error occurred.
CONSEQUENCES OF ERRORS
       Default.
       The following sections are informative.
APPLICATION USAGE
       The name init used for the system process is the most commonly used  on
       historical systems, but it may vary.
       The  ``domain  of  accessibility''  referred to is a broad concept that
       permits interpretation either on a very secure basis or even to allow a
       network-wide implementation like the historical rwho.
EXAMPLES
       None.
RATIONALE
       Due to differences between historical implementations, the base options
       provided were a compromise to allow users to work with those functions.
       The  standard  developers also considered removing all the options, but
       felt that these options offered  users  valuable  functionality.  Addi-
       tional options to match historical systems are available on XSI-confor-
       mant systems.
       It is recognized that the who command may  be  of  limited  usefulness,
       especially in a multi-level secure environment. The standard developers
       considered, however, that having some standard  method  of  determining
       the ``accessibility'' of other users would aid user portability.
       No format was specified for the default who output for systems not sup-
       porting the XSI option. In such a user-oriented command, designed  only
       for human use, this was not considered to be a deficiency.
       The format of the terminal name is unspecified, but the descriptions of
       ps, talk, and write require that they use the same format.
       It is acceptable for an implementation to  produce  no  output  for  an
       invocation of who mil.
FUTURE DIRECTIONS
       None.
SEE ALSO
       mesg
       The  Base  Definitions  volume  of POSIX.1-2008, Chapter 8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.unix.org/online.html .
       Any  typographical  or  formatting  errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files  to  man page format. To report such errors, see https://www.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                              WHO(1P)