STRINGS(1P) POSIX Programmer's Manual STRINGS(1P)
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NAME
strings -- find printable strings in files
SYNOPSIS
strings [-a] [-t format] [-n number] [file...]
DESCRIPTION
The strings utility shall look for printable strings in regular files
and shall write those strings to standard output. A printable string is
any sequence of four (by default) or more printable characters termi-
nated by a <newline> or NUL character. Additional implementation-
defined strings may be written; see localedef.
If the first argument is '-', the results are unspecified.
OPTIONS
The strings utility shall conform to the Base Definitions volume of
POSIX.1-2008, Section 12.2, Utility Syntax Guidelines, except for the
unspecified usage of '-'.
The following options shall be supported:
-a Scan files in their entirety. If -a is not specified, it is
implementation-defined what portion of each file is scanned
for strings.
-n number Specify the minimum string length, where the number argument
is a positive decimal integer. The default shall be 4.
-t format Write each string preceded by its byte offset from the start
of the file. The format shall be dependent on the single
character used as the format option-argument:
d The offset shall be written in decimal.
o The offset shall be written in octal.
x The offset shall be written in hexadecimal.
OPERANDS
The following operand shall be supported:
file A pathname of a regular file to be used as input. If no file
operand is specified, the strings utility shall read from the
standard input.
STDIN
See the INPUT FILES section.
INPUT FILES
The input files named by the utility arguments or the standard input
shall be regular files of any format.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of
strings:
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 and input
files) and to identify printable strings.
LC_MESSAGES
Determine the locale that should be used to affect the format
and contents of diagnostic messages written to standard
error.
NLSPATH Determine the location of message catalogs for the processing
of LC_MESSAGES.
ASYNCHRONOUS EVENTS
Default.
STDOUT
Strings found shall be written to the standard output, one per line.
When the -t option is not specified, the format of the output shall be:
"%s", <string>
With the -t o option, the format of the output shall be:
"%o %s", <byte offset>, <string>
With the -t x option, the format of the output shall be:
"%x %s", <byte offset>, <string>
With the -t d option, the format of the output shall be:
"%d %s", <byte offset>, <string>
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
By default the data area (as opposed to the text, ``bss'', or header
areas) of a binary executable file is scanned. Implementations document
which areas are scanned.
Some historical implementations do not require NUL or <newline> termi-
nators for strings to permit those languages that do not use NUL as a
string terminator to have their strings written.
EXAMPLES
None.
RATIONALE
Apart from rationalizing the option syntax and slight difficulties with
object and executable binary files, strings is specified to match his-
torical practice closely. The -a and -n options were introduced to
replace the non-conforming - and -number options. These options are no
longer specified by POSIX.1-2008 but may be present in some implementa-
tions.
The -o option historically means different things on different imple-
mentations. Some use it to mean ``offset in decimal'', while others use
it as ``offset in octal''. Instead of trying to decide which way would
be least objectionable, the -t option was added. It was originally
named -O to mean ``offset'', but was changed to -t to be consistent
with od.
The ISO C standard function isprint() is restricted to a domain of
unsigned char. This volume of POSIX.1-2008 requires implementations to
write strings as defined by the current locale.
FUTURE DIRECTIONS
None.
SEE ALSO
localedef, nm
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 STRINGS(1P)
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