/usr/share/zsh/5.5.1/help
Edit: /usr/share/zsh/5.5.1/help/ulimit (3173B)
ulimit [ -HSa ] [ { -bcdfiklmnpqrsTtvwx | -N resource } [ limit ] ... ]
Set or display resource limits of the shell and the processes
started by the shell. The value of limit can be a number in the
unit specified below or one of the values `unlimited', which
removes the limit on the resource, or `hard', which uses the
current value of the hard limit on the resource.
By default, only soft limits are manipulated. If the -H flag is
given use hard limits instead of soft limits. If the -S flag is
given together with the -H flag set both hard and soft limits.
If no options are used, the file size limit (-f) is assumed.
If limit is omitted the current value of the specified resources
are printed. When more than one resource value is printed, the
limit name and unit is printed before each value.
When looping over multiple resources, the shell will abort imme-
diately if it detects a badly formed argument. However, if it
fails to set a limit for some other reason it will continue try-
ing to set the remaining limits.
Not all the following resources are supported on all systems.
Running ulimit -a will show which are supported.
-a Lists all of the current resource limits.
-b Socket buffer size in bytes (N.B. not kilobytes)
-c 512-byte blocks on the size of core dumps.
-d Kilobytes on the size of the data segment.
-f 512-byte blocks on the size of files written.
-i The number of pending signals.
-k The number of kqueues allocated.
-l Kilobytes on the size of locked-in memory.
-m Kilobytes on the size of physical memory.
-n open file descriptors.
-p The number of pseudo-terminals.
-q Bytes in POSIX message queues.
-r Maximum real time priority. On some systems where this
is not available, such as NetBSD, this has the same
effect as -T for compatibility with sh.
-s Kilobytes on the size of the stack.
-T The number of simultaneous threads available to the user.
-t CPU seconds to be used.
-u The number of processes available to the user.
-v Kilobytes on the size of virtual memory. On some systems
this refers to the limit called `address space'.
-w Kilobytes on the size of swapped out memory.
-x The number of locks on files.
A resource may also be specified by integer in the form `-N
resource', where resource corresponds to the integer defined for
the resource by the operating system. This may be used to set
the limits for resources known to the shell which do not corre-
spond to option letters. Such limits will be shown by number in
the output of `ulimit -a'.
The number may alternatively be out of the range of limits com-
piled into the shell. The shell will try to read or write the
limit anyway, and will report an error if this fails.