fish-shell/doc_src/cmds/ulimit.rst

.. _cmd-ulimit:

ulimit - set or get resource usage limits
=========================================

Synopsis
--------

.. synopsis::

    ulimit [OPTIONS] [LIMIT]


Description
-----------

``ulimit`` sets or outputs the resource usage limits of the shell and any processes spawned by it. If a new limit value is omitted, the current value of the limit of the resource is printed; otherwise, the specified limit is set to the new value.

Use one of the following switches to specify which resource limit to set or report:

**-b** or **--socket-buffers**
    The maximum size of socket buffers.

**-c** or **--core-size**
    The maximum size of core files created. By setting this limit to zero, core dumps can be disabled.

**-d** or **--data-size**
    The maximum size of a process' data segment.

**-e** or **--nice**
    Controls the maximum nice value; on Linux, this value is subtracted from 20 to give the effective value.

**-f** or **--file-size**
    The maximum size of files created by a process.

**-i** or **--pending-signals**
    The maximum number of signals that may be queued.

**-l** or **--lock-size**
    The maximum size that may be locked into memory.

**-m** or **--resident-set-size**
    The maximum resident set size.

**-n** or **--file-descriptor-count**
    The maximum number of open file descriptors.

**-q** or **--queue-size**
    The maximum size of data in POSIX message queues.

**-r** or **--realtime-priority**
    The maximum realtime scheduling priority.

**-s** or **--stack-size**
    The maximum stack size.

**-t** or **--cpu-time**
    The maximum amount of CPU time in seconds.

**-u** or **--process-count**
    The maximum number of processes available to the current user.

**-w** or **--swap-size**
    The maximum swap space available to the current user.

**-v** or **--virtual-memory-size**
    The maximum amount of virtual memory available to the shell.

**-y** or **--realtime-maxtime**
    The maximum contiguous realtime CPU time in microseconds.

**-K** or **--kernel-queues**
    The maximum number of kqueues (kernel queues) for the current user.

**-P** or **--ptys**
    The maximum number of pseudo-terminals for the current user.

**-T** or **--threads**
    The maximum number of simultaneous threads for the current user.

Note that not all these limits are available in all operating systems; consult the documentation for ``setrlimit`` in your operating system.

The value of limit can be a number in the unit specified for the resource or one of the special values ``hard``, ``soft``, or ``unlimited``, which stand for the current hard limit, the current soft limit, and no limit, respectively.

If limit is given, it is the new value of the specified resource. If no option is given, then **-f** is assumed. Values are in kilobytes, except for **-t**, which is in seconds and **-n** and **-u**, which are unscaled values. The exit status is 0 unless an invalid option or argument is supplied, or an error occurs while setting a new limit.

``ulimit`` also accepts the following options that determine what type of limit to set:

**-H** or **--hard**
    Sets hard resource limit.

**-S** or **--soft**
    Sets soft resource limit.

A hard limit can only be decreased. Once it is set it cannot be increased; a soft limit may be increased up to the value of the hard limit. If neither **-H** nor **-S** is specified, both the soft and hard limits are updated when assigning a new limit value, and the soft limit is used when reporting the current value.

The following additional options are also understood by ``ulimit``:

**-a** or **--all**
    Prints all current limits.

**-h** or **--help**
    Displays help about using this command.

The ``fish`` implementation of ``ulimit`` should behave identically to the implementation in bash, except for these differences:

- Fish ``ulimit`` supports GNU-style long options for all switches.

- Fish ``ulimit`` does not support the **-p** option for getting the pipe size. The bash implementation consists of a compile-time check that empirically guesses this number by writing to a pipe and waiting for SIGPIPE. Fish does not do this because this method of determining pipe size is unreliable. Depending on bash version, there may also be further additional limits to set in bash that do not exist in fish.

- Fish ``ulimit`` does not support getting or setting multiple limits in one command, except reporting all values using the **-a** switch.


Example
-------

``ulimit -Hs 64`` sets the hard stack size limit to 64 kB.
docs: Add labels to all commands This allows us to use :ref: references, which don't require hardcoding it as html [ci skip] 2019-03-31 17:05:09 +08:00			`.. _cmd-ulimit:`

Switch command docs from \section to reStructuredText 2018-12-17 09:39:33 +08:00			`ulimit - set or get resource usage limits`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`=========================================`
Switch command docs from \section to reStructuredText 2018-12-17 09:39:33 +08:00
Migrate the 'synopsis' sections to .rst format 2018-12-18 09:58:24 +08:00			`Synopsis`
			`--------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs synopsis: add HTML highlighing and automate manpage markup Recent synopsis changes move from literal code blocks to [RST line blocks]. This does not translate well to HTML: it's not rendered in monospace, so aligment is lost. Additionally, we don't get syntax highlighting in HTML, which adds differences to our code samples which are highlighted. We hard-wrap synopsis lines (like code blocks). To align continuation lines in manpages we need [backslashes in weird places]. Combined with the *, , and `` markup, it's a bit hard to get the alignment right. Fix these by moving synopsis sources back to code blocks and compute HTML syntax highlighting and manpage markup with a custom Sphinx extension. The new Pygments lexer can tokenize a synopsis and assign the various highlighting roles, which closely matches fish's syntax highlighing: - command/keyword (dark blue) - parameter (light blue) - operator like and/or/not/&&/\|\| (cyan) - grammar metacharacter (black) For manpage output, we don't project the fish syntax highlighting but follow the markup convention in GNU's man(1): bold text type exactly as shown. italic text replace with appropriate argument. To make it easy to separate these two automatically, formalize that (italic) placeholders must be uppercase; while all lowercase text is interpreted literally (so rendered bold). This makes manpages more consistent, see string-join(1) and and(1). Implementation notes: Since we want manpage formatting but Sphinx's Pygments highlighing plugin does not support manpage output, add our custom "synopsis" directive. This directive parses differently when manpage output is specified. This means that the HTML and manpage build processes must not share a cache, because the parsed doctrees are cached. Work around this by using separate cache locations for build targets "sphinx-docs" (which creates HTML) and "sphinx-manpages". A better solution would be to only override Sphinx's ManualPageBuilder but that would take a bit more code (ideally we could override ManualPageWriter but Sphinx 4.3.2 doesn't really support that). --- Alternative solution: stick with line blocks but use roles like :command: or :option: (or custom ones). While this would make it possible to produce HTML that is consistent with code blocks (by adding a bit of CSS), the source would look uglier and is harder to maintain. (Let's say we want to add custom formatting to the [\|] metacharacters in HTML. This is much easier with the proposed patch.) --- [RST line blocks]: https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#line-blocks [backslashes in weird places]: https://github.com/fish-shell/fish-shell/pull/8626#discussion_r782837750 2022-01-09 22:09:46 +08:00			`.. synopsis::`

docs synopsis: make all placeholder arguments uppercase man(1) uses lowercase placeholders but we usually don't. Additionally, the new synopsis autoformatting only recognizes placeholders if they are uppercase. Use uppercase for all placeholders. 2022-01-17 12:29:49 +08:00			`ulimit [OPTIONS] [LIMIT]`
Migrate the 'synopsis' sections to .rst format 2018-12-18 09:58:24 +08:00
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Convert \\subsection sections into rst format 2018-12-19 10:44:30 +08:00			`Description`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`-----------`
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docs: Link builtins When we say "the XYZ command/builtin", we should typically include a link. The exceptions are - In the documentation for that command - no need to link to ulimit in the ulimit page - When we've already linked before - not every thing needs to be clickable, or clicking it will cause the browser to mark fifty words as visited. This is roughly what wikipedia does for crosslinks. [ci skip] 2020-03-21 22:31:25 +08:00			``ulimit`` sets or outputs the resource usage limits of the shell and any processes spawned by it. If a new limit value is omitted, the current value of the limit of the resource is printed; otherwise, the specified limit is set to the new value.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
			`Use one of the following switches to specify which resource limit to set or report:`

ulimit: add new limits from FreeBSD/NetBSD Short option names are taken from sh for those platforms where possible. 2022-03-23 21:49:09 +08:00			`-b or --socket-buffers`
			`The maximum size of socket buffers.`

docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-c or --core-size`
			`The maximum size of core files created. By setting this limit to zero, core dumps can be disabled.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-d or --data-size`
			`The maximum size of a process' data segment.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
ulimit: add new limits from Linux Short options are taken from prlimit(1) where appropriate. Closes #8786. 2022-03-21 23:36:41 +08:00			`-e or --nice`
			`Controls the maximum nice value; on Linux, this value is subtracted from 20 to give the effective value.`

docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-f or --file-size`
ulimit: some corrections to descriptions and documentation 2022-03-21 23:33:47 +08:00			`The maximum size of files created by a process.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
ulimit: add new limits from Linux Short options are taken from prlimit(1) where appropriate. Closes #8786. 2022-03-21 23:36:41 +08:00			`-i or --pending-signals`
			`The maximum number of signals that may be queued.`

docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-l or --lock-size`
			`The maximum size that may be locked into memory.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-m or --resident-set-size`
			`The maximum resident set size.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-n or --file-descriptor-count`
ulimit: some corrections to descriptions and documentation 2022-03-21 23:33:47 +08:00			`The maximum number of open file descriptors.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
ulimit: add new limits from Linux Short options are taken from prlimit(1) where appropriate. Closes #8786. 2022-03-21 23:36:41 +08:00			`-q or --queue-size`
			`The maximum size of data in POSIX message queues.`

			`-r or --realtime-priority`
			`The maximum realtime scheduling priority.`

docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-s or --stack-size`
			`The maximum stack size.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-t or --cpu-time`
			`The maximum amount of CPU time in seconds.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-u or --process-count`
ulimit: some corrections to descriptions and documentation 2022-03-21 23:33:47 +08:00			`The maximum number of processes available to the current user.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
ulimit: add new limits from FreeBSD/NetBSD Short option names are taken from sh for those platforms where possible. 2022-03-23 21:49:09 +08:00			`-w or --swap-size`
			`The maximum swap space available to the current user.`

docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-v or --virtual-memory-size`
			`The maximum amount of virtual memory available to the shell.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
ulimit: add new limits from Linux Short options are taken from prlimit(1) where appropriate. Closes #8786. 2022-03-21 23:36:41 +08:00			`-y or --realtime-maxtime`
			`The maximum contiguous realtime CPU time in microseconds.`

ulimit: add new limits from FreeBSD/NetBSD Short option names are taken from sh for those platforms where possible. 2022-03-23 21:49:09 +08:00			`-K or --kernel-queues`
			`The maximum number of kqueues (kernel queues) for the current user.`

			`-P or --ptys`
			`The maximum number of pseudo-terminals for the current user.`

			`-T or --threads`
			`The maximum number of simultaneous threads for the current user.`

			Note that not all these limits are available in all operating systems; consult the documentation for ``setrlimit`` in your operating system.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			The value of limit can be a number in the unit specified for the resource or one of the special values ``hard``, ``soft``, or ``unlimited``, which stand for the current hard limit, the current soft limit, and no limit, respectively.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`If limit is given, it is the new value of the specified resource. If no option is given, then -f is assumed. Values are in kilobytes, except for -t, which is in seconds and -n and -u, which are unscaled values. The exit status is 0 unless an invalid option or argument is supplied, or an error occurs while setting a new limit.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
ulimit: some corrections to descriptions and documentation 2022-03-21 23:33:47 +08:00			``ulimit`` also accepts the following options that determine what type of limit to set:
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-H or --hard`
			`Sets hard resource limit.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-S or --soft`
			`Sets soft resource limit.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`A hard limit can only be decreased. Once it is set it cannot be increased; a soft limit may be increased up to the value of the hard limit. If neither -H nor -S is specified, both the soft and hard limits are updated when assigning a new limit value, and the soft limit is used when reporting the current value.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			The following additional options are also understood by ``ulimit``:
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: standardise on definition lists for options Harmonizes the option listing including formatting in a similar manner to the synopsis of each entry. 2022-03-11 23:56:20 +08:00			`-a or --all`
			`Prints all current limits.`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: omnibus cleanup Includes harmonizing the display of options and arguments, standardising terminology, using the envvar directive more broadly, adding help options to all commands that support them, simplifying some language, and tidying up multiple formatting issues. string documentation is not changed. 2022-03-12 00:18:41 +08:00			`-h or --help`
			`Displays help about using this command.`

Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			The ``fish`` implementation of ``ulimit`` should behave identically to the implementation in bash, except for these differences:
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: omnibus cleanup Includes harmonizing the display of options and arguments, standardising terminology, using the envvar directive more broadly, adding help options to all commands that support them, simplifying some language, and tidying up multiple formatting issues. string documentation is not changed. 2022-03-12 00:18:41 +08:00			- Fish ``ulimit`` supports GNU-style long options for all switches.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: Fix typos 2022-09-17 19:38:33 +08:00			- Fish ``ulimit`` does not support the -p option for getting the pipe size. The bash implementation consists of a compile-time check that empirically guesses this number by writing to a pipe and waiting for SIGPIPE. Fish does not do this because this method of determining pipe size is unreliable. Depending on bash version, there may also be further additional limits to set in bash that do not exist in fish.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: omnibus cleanup Includes harmonizing the display of options and arguments, standardising terminology, using the envvar directive more broadly, adding help options to all commands that support them, simplifying some language, and tidying up multiple formatting issues. string documentation is not changed. 2022-03-12 00:18:41 +08:00			- Fish ``ulimit`` does not support getting or setting multiple limits in one command, except reporting all values using the -a switch.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00

Convert \\subsection sections into rst format 2018-12-19 10:44:30 +08:00			`Example`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`-------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			``ulimit -Hs 64`` sets the hard stack size limit to 64 kB.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00