ulimit - get and set process limits
long ulimit(int cmd, /* newlimit */...);
The ulimit() function provides for control over process lim-
its. It is effective in limiting the growth of regular
files. Pipes are limited to PIPE_MAX bytes.
The cmd values, defined in <ulimit.h>, include:
Return the soft file size limit of the process. The
limit is in units of 512-byte blocks and is inherited
by child processes. Files of any size can be read. The
return value is the integer part of the soft file size
limit divided by 512. If the result cannot be
represented as a long int, the result is unspecified.
Set the hard and soft file size limits for output
operations of the process to the value of the second
argument, taken as a long int. Any process may
decrease its own hard limit, but only a process with
appropriate privileges may increase the limit. The new
file size limit is returned. The hard and soft file
size limits are set to the specified value multiplied
by 512. If the result would overflow an rlimit_t, the
actual value set is unspecified.
Get the maximum possible break value (see brk(2)).
Get the current value of the maximum number of open
files per process configured in the system.
Upon successful completion, ulimit() returns the value of
the requested limit. Otherwise, -1 is returned, the limit
is not changed, and errno is set to indicate the error.
The ulimit() function will fail if:
The cmd argument is not valid.
EPERM A process not having appropriate privileges attempts
to increase its file size limit.
Since all return values are permissible in a successful
situation, an application wishing to check for error situa-
tions should set errno to 0, then call ulimit(), and if it
returns -1, check if errno is non-zero.
The getrlimit() and setrlimit() functions provide a more
general interface for controlling process limits, and are
preferred over ulimit(). See getrlimit(2).
brk(2), getrlimit(2), write(2)
Man(1) output converted with