ulimit(3)ulimit(3)NAMEulimit - Set and gets process limits
long int ulimit(
Standard C Library (libc)
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
Specifies the form of control. The command parameter can have the fol‐
lowing values: Returns the soft file size limit of the process. The
limit is reported in 512-byte blocks (see the sys/param.h file) and is
inherited by child processes. The function can read files of any size.
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. Sets the hard and soft process
file size limit for output operations to the value of the second
parameter, taken as a long int value, and returns the new file
size limit. Any process can decrease its own hard limit, but
only a process with the privileges can increase the limit.
The hard and soft file size limits are set to the specified
value multiplied by 512. If the result would overflow an rlim_t,
the actual value set is unspecified. [Tru64 UNIX] Returns the
maximum possible break value as described in the brk(2) refer‐
The ulimit() function controls process limits.
During access to remote files, the process limits of the local node are
The ulimit() function is implemented with calls to setrlimit(). The two
interfaces should not be used in the same program. The result of doing
so is undefined.
Upon successful completion, ulimit() returns the value of the requested
limit and does not change the setting of errno. Otherwise, a value of
-1 is returned, and errno is set to indicate the error.
If the ulimit() function fails, the limit remains unchanged and errno
is set to one of the following values: The command parameter is
invalid. A process without appropriate system privileges attempted to
increase its file size limit.
As all return values are permissable in a successful situation, an
application wishing to check for error situations should set errno to
0, then call ulimit(), and, if it returns -1, check to see if errno is
Functions: brk(2), getrlimit(2), write(2)