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ULIMIT(3P) POSIX Programmer's Manual ULIMIT(3P)
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.
ulimit — get and set process limits
#include <ulimit.h>
long ulimit(int cmd, ...);
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.
Upon successful completion, ulimit() shall return the value of the
requested limit. Otherwise, −1 shall be returned and errno set to
indicate the error.
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.
None.
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.
None.
The ulimit() function may be removed in a future version.
exec(1p), getrlimit(3p), write(3p)
The Base Definitions volume of POSIX.1‐2008, ulimit.h(0p)
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 Electrical 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.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 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)