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.
NAMEulimit — 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 setr‐
limit() 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 appro‐
priate 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 success‐
ful.
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 indi‐
cate 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, getrlimit(), write()
The Base Definitions volume of POSIX.1‐2008, <ulimit.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 ULIMIT(3P)
