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STRINGS(1P) POSIX Programmer's Manual STRINGS(1P)

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (con-
sult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on
Linux.

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 terminated by a <newline> or NUL char-
acter. Additional implementation-defined strings may be written; see localedef.

OPTIONS
The strings utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2, Utility Syntax
Guidelines.

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 variables that are unset or null. (See the Base Definitions
volume of IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the precedence of international-
ization 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 stan-
dard 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. Imple-
mentations document which areas are scanned.

Some historical implementations do not require NUL or <newline> terminators 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 historical practice closely. The -a and -n options were introduced to replace the non-conforming - and
- number options.

The -o option historically means different things on different implementations. 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 IEEE Std 1003.1-2001
requires implementations to write strings as defined by the current locale.

FUTURE DIRECTIONS
None.