ULIMIT(P) POSIX Programmer's Manual ULIMIT(P)
ulimit - get and set process limits
long ulimit(int cmd, ...);
The ulimit() function shall control process limits. The process limits that can be con-
trolled 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
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
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. Other-
wise, -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
The following sections are informative.
getrlimit() , setrlimit() , write() , the Base Definitions volume of IEEE Std 1003.1-2001,
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 ULIMIT(P)