ULIMIT(2) System Calls ULIMIT(2)

NAME

ulimit - get and set process limits

SYNOPSIS

#include <ulimit.h>

long ulimit(int cmd, /* newlimit */...);

DESCRIPTION

The ulimit() function provides for control over process limits. It is
effective in limiting the growth of regular files. Pipes are limited to
PIPE_MAX bytes.


The cmd values, defined in <ulimit.h>, include:

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


UL_SETFSIZE
Set the hard and soft file size limits for output
operations of the process to the value of the second
argument, taken as a long int. Any process may decrease
its own hard limit, but only a process with appropriate
privileges may increase the limit. The new file size limit
is returned. The hard and soft file size limits are set to
the specified value multiplied by 512. If the result
would overflow an rlimit_t, the actual value set is
unspecified.


UL_GMEMLIM
Get the maximum possible break value (see brk(2)).


UL_GDESLIM
Get the current value of the maximum number of open files
per process configured in the system.

RETURN VALUES

Upon successful completion, ulimit() returns the value of the requested
limit. Otherwise, -1 is returned, the limit is not changed, and errno is
set to indicate the error.

ERRORS

The ulimit() function will fail if:

EINVAL
The cmd argument is not valid.


EPERM
A process that has not asserted {PRIV_SYS_RESOURCE} in its
effective set is trying to increase its file size limit.

USAGE

Since 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 if errno is non-zero.


The getrlimit() and setrlimit() functions provide a more general
interface for controlling process limits, and are preferred over
ulimit(). See getrlimit(2).

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+

SEE ALSO

brk(2), getrlimit(2), write(2), attributes(7), privileges(7),
standards(7)

February 1, 2003 ULIMIT(2)