'\" et
.TH ULIMIT "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH 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.
.\"
.SH NAME
ulimit
\(em get and set process limits
.SH SYNOPSIS
.LP
.nf
#include <ulimit.h>
.P
long ulimit(int \fIcmd\fP, ...);
.fi
.SH DESCRIPTION
The
\fIulimit\fR()
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
\fIsetrlimit\fR()
with RLIMIT_FSIZE). The
.IR cmd
values, defined in
.IR <ulimit.h> ,
include:
.IP UL_GETFSIZE 12
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
.BR long ,
the result is unspecified.
.IP UL_SETFSIZE 12
Set the file size limit for output operations of the process to the
value of the second argument, taken as a
.BR long ,
multiplied by 512. If the result would overflow an
.BR 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.
.P
The
\fIulimit\fR()
function shall not change the setting of
.IR errno
if successful.
.P
As all return values are permissible in a successful situation, an
application wishing to check for error situations should set
.IR errno
to 0, then call
\fIulimit\fR(),
and, if it returns \-1, check to see if
.IR errno
is non-zero.
.SH "RETURN VALUE"
Upon successful completion,
\fIulimit\fR()
shall return the value of the requested limit. Otherwise, \-1
shall be returned and
.IR errno
set to indicate the error.
.SH ERRORS
The
\fIulimit\fR()
function shall fail and the limit shall be unchanged if:
.TP
.BR EINVAL
The
.IR cmd
argument is not valid.
.TP
.BR EPERM
A process not having appropriate privileges attempts to increase its
file size limit.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
Since the
\fIulimit\fR()
function uses type
.BR long
rather than
.BR rlim_t ,
this function is not sufficient for file sizes on many current systems.
Applications should use the
\fIgetrlimit\fR()
or
\fIsetrlimit\fR()
functions instead of the obsolescent
\fIulimit\fR()
function.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
The
\fIulimit\fR()
function may be removed in a future version.
.SH "SEE ALSO"
.IR "\fIexec\fR\^",
.IR "\fIgetrlimit\fR\^(\|)",
.IR "\fIwrite\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<ulimit.h>\fP"
.\"
.SH 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 .
.PP
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 .