-n
The maximum number of open file descriptors (most systems do not allow this value to be set).
-p
The pipe buffer size.
-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, and, on some systems, to its children.
-x
The maximum number of file locks.
-T
The maximum number of threads.
If limit is given, and the -a option is not used, limit is the new value of the specified resource. The special limit values hard, soft, and unlimited stand for the current hard limit, the current soft limit, and no limit, respectively. A hard limit cannot be increased by a non-root user once it is set; a soft limit may be increased up to the value of the hard limit. Otherwise, the current value of the soft limit for the specified resource is printed, unless the -H option is supplied. When setting new limits, if neither -H nor -S is supplied, both the hard and soft limits are set. 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 -T, -b, -n and -u, which are unscaled values.
The return status is zero unless an invalid option or argument is supplied, or an error occurs while setting a new limit. unalias unalias [-a] [name ... ]
Remove each name from the list of aliases. If -a is supplied, all aliases are removed. Aliases are described in Section 6.6 [Aliases], page 88.
4.3 Modifying Shell Behavior
4.3.1 The Set Builtin
This builtin is so complicated that it deserves its own section. set allows you to change the values of shell options and set the positional parameters, or to display the names and values of shell variables. set set [--abefhkmnptuvxBCEHPT] [-o option-name] [argument ...] set [+abefhkmnptuvxBCEHPT] [+o option-name] [argument ...]
If no options or arguments are supplied, set displays the names and values of all shell variables and functions, sorted according to the current locale, in a format