Updated: 2021/Apr/14

ULIMIT(3)                  Library Functions Manual                  ULIMIT(3)

     ulimit - get and set process limits

     Standard C Library (libc, -lc)

     #include <ulimit.h>

     long int
     ulimit(int cmd, ...);

     The ulimit() function provides a method to query or alter resource limits
     of the calling process.  The method to be performed is specified by the
     cmd argument; possible values are:

     UL_GETFSIZE    Return the soft file size limit of the process.  The value
                    returned is in units of 512-byte blocks.  If the result
                    cannot be represented in an object of type long int, the
                    result is unspecified.

     UL_SETFSIZE    Set the hard and soft file size limits of the process to
                    the value of the second argument passed, which is in units
                    of 512-byte blocks, and which is expected to be of type
                    long int.  The new file size limit of the process is
                    returned.  Any process may decrease the limit, but raising
                    it is only permitted if the caller is the super-user.

     If successful, the ulimit() function will not change the setting of

     If successful, the ulimit() function returns the value of the requested
     limit.  Otherwise, it returns -1, sets errno to indicate an error, and
     the limit is not changed.  Therefore, to detect an error condition
     applications should set errno to 0, call ulimit(), and check if -1 is
     returned and errno is non-zero.

     The ulimit() function will fail if:

     [EINVAL]           The cmd argument is not valid.

     [EPERM]            It was attempted to increase a limit, and the caller
                        is not the super-user.

     getrlimit(2), setrlimit(2)

     The ulimit() function conforms to X/Open System Interfaces and Headers
     Issue 5 ("XSH5") and IEEE Std 1003.1-2001 ("POSIX.1").  It was marked as
     obsolete in the IEEE Std 1003.1-2008 ("POSIX.1") revision, which
     recommended the use of getrlimit(2) and setrlimit(2) instead, noting that
     because ulimit() uses the type long rather than rlim_t, it may not be
     sufficient for file sizes on many current systems.

NetBSD 9.99                     April 30, 2010                     NetBSD 9.99