Manual Reference Linux

  • ulimit
  • ulimit [-SHacdefilmnpqrstuvx [limit]]
    Provides control over the resources available to the shell and to processes started by it, on sys-
    tems that allow such control. 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 lim-
    its 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 speci-
    fied, the limit name and unit are printed before the value. Other options are interpreted as fol-
    lows:
    -a All current limits are reported
    -c The maximum size of core files created
    -d The maximum size of a process√Ęs data segment
    -e The maximum scheduling priority (“nice”)
    -f The maximum size of files written by the shell and its children
    -i The maximum number of pending signals
    -l The maximum size that may be locked into memory
    -m The maximum resident set size (has no effect on Linux)
    -n The maximum number of open file descriptors (most systems do not allow this value to be set)
    -p The pipe size in 512-byte blocks (this may not be set)
    -q The maximum number of bytes in POSIX message queues
    -r The maximum real-time scheduling priority
    -s The maximum stack size
    -t The maximum amount of cpu time in seconds
    -u The maximum number of processes available to a single user
    -v The maximum amount of virtual memory available to the shell
    -x The maximum number of file locks

    If limit is given, it is the new value of the specified resource (the -a option is display only).
    If no option is given, then -f is assumed. Values are in 1024-byte increments, except for -t,
    which is in seconds, -p, which is in units of 512-byte blocks, 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.

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