ULIMIT(1POSIX)

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
ulimit — set or report file size limit

SYNOPSIS

ulimit [-f] [blocks]

DESCRIPTION
The ulimit utility shall set or report the file-size writing limit imposed on files written by the shell and its child processes (files of any size may be read). Only a process with appropriate privileges can increase the limit.

OPTIONS
The ulimit utility shall conform to the Base Definitions volume of POSIX.1-2017, Section 12.2, Utility Syntax Guidelines.

The following option shall be supported:

-f  Set (or report, if no blocks operand is present), the file size limit in blocks. The -f option shall also be the default case.

OPERANDS
The following operand shall be supported:

blocks
    The number of 512-byte blocks to use as the new file size limit.

STDIN
Not used.

INPUT FILES
None.

ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of ulimit:

LANG
    Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of POSIX.1-2017, Section 8.2, Internationalization Variables 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.

NLSPATH
    Determine the location of message catalogs for the processing of LC_MESSAGES.

ASYNCHRONOUS EVENTS
Default.

STDOUT
The standard output shall be used when no blocks operand is present. If the current number of blocks is limited, the number of blocks in the current limit shall be written in the following format:

    "%d\n", <number of 512-byte blocks>

If there is no current limit on the number of blocks, in the POSIX locale the following format shall be used:

    "unlimited\n"

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  A request for a higher limit was rejected or an error occurred.

CONSEQUENCES OF ERRORS
Default.

The following sections are informative.

APPLICATION USAGE
Since ulimit affects the current shell execution environment, it is always provided as a shell regular built-in. If it is called in a separate utility execution environment, such as one of the following:

    nohup ulimit -f 10000
    env ulimit 10000

it does not affect the file size limit of the caller's environment.

Once a limit has been decreased by a process, it cannot be increased (unless appropriate privileges are involved), even back to the original system limit.

EXAMPLES
Set the file size limit to 51200 bytes:

    ulimit -f 100

RATIONALE
None.

FUTURE DIRECTIONS
None.

SEE ALSO
The Base Definitions volume of POSIX.1-2017, Chapter 8, Environment Variables, Section 12.2, Utility Syntax Guidelines

The System Interfaces volume of POSIX.1-2017, ulimit()

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. 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.opengroup.org/unix/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.kernel.org/doc/man-pages/reporting_bugs.html .