fish-shell/doc_src/ulimit.txt

\section ulimit ulimit - Set or get the shells resurce usage limits

\subsection ulimit-synopsis Synopsis
<tt>ulimit [OPTIONS] [LIMIT]</tt>

\subsection ulimit-description Description

The ulimit builtin provides control over the resources available to
the shell and to processes started by it. The -H and -S options
specify that the hard or soft limit is set for the given resource. A
hard limit cannot be increased once it is set; 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 set. 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 omitted, the current value of the soft limit of the resource
is printed, unless the -H option is given.  When more than one
resource is specified, the limit name and unit are printed before the
value. Other options are interpreted as follows:

- <code>-a</code> or <code>--all</code> Set or get all current limits
- <code>-c</code> or <code>--core-size</code> The maximum size of core files created
- <code>-d</code> or <code>--data-size</code> The maximum size of a process’s data segment
- <code>-f</code> or <code>--file-size</code> The maximum size of files created by the shell
- <code>-l</code> or <code>--lock-size</code> The maximum size that may be locked into memory
- <code>-m</code> or <code>--resident-set-size</code> The maximum resident set size
- <code>-n</code> or <code>--file-descriptor-count</code> The maximum number of open file descriptors (most systems do not allow this value to be set)
- <code>-s</code> or <code>--stack-size</code> The maximum stack size
- <code>-t</code> or <code>--cpu-time</code> The maximum amount of cpu time in seconds
- <code>-u</code> or <code>--process-count</code> The maximum number of processes available to a single user
- <code>-v</code> or <code>--virtual-memory-size</code> The maximum amount of virtual memory available to the shell. If supported by OS.

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 return status is 0 unless an invalid option or argument is
supplied, or an error occurs while setting a new limit.

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 ulimit does not support getting the values of multiple limits in one command, except by using the -a switch

\subsection ulimit-example Example

<tt>ulimit -Hs 64</tt>

would set the hard stack size limit to 64 kB: