ulimit(3p) — Linux manual page

ULIMIT(3P)              POSIX Programmer's Manual             ULIMIT(3P)

PROLOG

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME

       ulimit — get and set process limits

SYNOPSIS

       #include <ulimit.h>

       long ulimit(int cmd, ...);

DESCRIPTION

       The ulimit() function shall control process limits. The process
       limits that can be controlled by this function include the
       maximum size of a single file that can be written (this is
       equivalent to using setrlimit() with RLIMIT_FSIZE). The cmd
       values, defined in <ulimit.h>, include:

       UL_GETFSIZE Return the file size limit (RLIMIT_FSIZE) of the
                   process. The limit shall be in units of 512-byte
                   blocks and shall be inherited by child processes.
                   Files of any size can be read. The return value shall
                   be the integer part of the soft file size limit
                   divided by 512. If the result cannot be represented
                   as a long, the result is unspecified.

       UL_SETFSIZE Set the file size limit for output operations of the
                   process to the value of the second argument, taken as
                   a long, multiplied by 512. If the result would
                   overflow an rlim_t, the actual value set is
                   unspecified. Any process may decrease its own limit,
                   but only a process with appropriate privileges may
                   increase the limit. The return value shall be the
                   integer part of the new file size limit divided by
                   512.

       The ulimit() function shall not change the setting of errno if
       successful.

       As all return values are permissible 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 non-zero.

RETURN VALUE

       Upon successful completion, ulimit() shall return the value of
       the requested limit. Otherwise, -1 shall be returned and errno
       set to indicate the error.

ERRORS

       The ulimit() function shall fail and the limit shall be unchanged
       if:

       EINVAL The cmd argument is not valid.

       EPERM  A process not having appropriate privileges attempts to
              increase its file size limit.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Since the ulimit() function uses type long rather than rlim_t,
       this function is not sufficient for file sizes on many current
       systems.  Applications should use the getrlimit() or setrlimit()
       functions instead of the obsolescent ulimit() function.

RATIONALE

       None.

FUTURE DIRECTIONS

       The ulimit() function may be removed in a future version.

SEE ALSO

       exec(1p), getrlimit(3p), write(3p)

       The Base Definitions volume of POSIX.1‐2017, ulimit.h(0p)

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                        ULIMIT(3P)

Pages that refer to this page: ulimit.h(0p), sh(1p), ulimit(1p), exec(3p), fclose(3p), fflush(3p), fputc(3p), fputwc(3p), fseek(3p), getrlimit(3p), write(3p)

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