The ulimit(1) command is a built-in Korn shell
(ksh(1)) command that displays or sets process limits. The
Korn shell supports, through ulimit(1), all limits defined
by the setrlimit(2).
If no options are used, the file size limit (-f) is
assumed. The value n, if specified, can be either an
arithmetic expression or the word "unlimited." The limits affect
the shell and any processes created by the shell after a limit is
imposed. Note that some systems might not allow limits to be
increased once they are set.
-a
Displays all limits; unless -H is used, soft limits are
displayed.
-cn
Impose a size limit of n blocks on the size of core
dumps.
-dn
Impose a size limit of n kilobytes on the size of the
data area.
-fn
Impose a size limit of n blocks on files written by the
shell and its child processes (files of any size can be read).
-H
Set the hard limit only (default is to set both hard and soft
limits).
-nn
Impose a limit of n file descriptors that can be open at
once.
-sn
Impose a size limit of n kilobytes on the size of the
stack area.
-S
Set the soft limit only (default is to set both hard and soft
limits).
-tn
Impose a time limit of n CPU seconds to be used by each
process.
-vn
Impose a limit of n kilobytes on the amount of virtual
memory used; on some systems this is the maximum allowable virtual
address (in bytes, not kilobytes).