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OpenDarwin 7.2.1 - man page for setrlimit (opendarwin section 2)

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GETRLIMIT(2)			     BSD System Calls Manual			     GETRLIMIT(2)

NAME
     getrlimit, setrlimit -- control maximum system resource consumption

SYNOPSIS
     #include <sys/types.h>
     #include <sys/time.h>
     #include <sys/resource.h>

     int
     getrlimit(int resource, struct rlimit *rlp);

     int
     setrlimit(int resource, const struct rlimit *rlp);

DESCRIPTION
     Limits on the consumption of system resources by the current process and each process it
     creates may be obtained with the getrlimit() call, and set with the setrlimit() call.

     The resource parameter is one of the following:

     RLIMIT_CORE     The largest size (in bytes) core file that may be created.

     RLIMIT_CPU      The maximum amount of cpu time (in seconds) to be used by each process.

     RLIMIT_DATA     The maximum size (in bytes) of the data segment for a process; this defines
		     how far a program may extend its break with the sbrk(2) system call.

     RLIMIT_FSIZE    The largest size (in bytes) file that may be created.

     RLIMIT_MEMLOCK  The maximum size (in bytes) which a process may lock into memory using the
		     mlock(2) function.

     RLIMIT_NOFILE   The maximum number of open files for this process.

     RLIMIT_NPROC    The maximum number of simultaneous processes for this user id.

     RLIMIT_RSS      The maximum size (in bytes) to which a process's resident set size may grow.
		     This imposes a limit on the amount of physical memory to be given to a
		     process; if memory is tight, the system will prefer to take memory from pro-
		     cesses that are exceeding their declared resident set size.

     RLIMIT_STACK    The maximum size (in bytes) of the stack segment for a process; this defines
		     how far a program's stack segment may be extended.  Stack extension is per-
		     formed automatically by the system.

     A resource limit is specified as a soft limit and a hard limit.  When a soft limit is
     exceeded a process may receive a signal (for example, if the cpu time or file size is
     exceeded), but it will be allowed to continue execution until it reaches the hard limit (or
     modifies its resource limit).  The rlimit structure is used to specify the hard and soft
     limits on a resource,

	   struct rlimit {
		   rlim_t  rlim_cur;	   /* current (soft) limit */
		   rlim_t  rlim_max;	   /* hard limit */
	   };

     Only the super-user may raise the maximum limits.	Other users may only alter rlim_cur
     within the range from 0 to rlim_max or (irreversibly) lower rlim_max.

     An ``infinite'' value for a limit is defined as RLIM_INFINITY.

     Because this information is stored in the per-process information, this system call must be
     executed directly by the shell if it is to affect all future processes created by the shell;
     limit is thus a built-in command to csh(1) and ulimit is the sh(1) equivalent.

     The system refuses to extend the data or stack space when the limits would be exceeded in
     the normal way: a break call fails if the data space limit is reached.  When the stack limit
     is reached, the process receives a segmentation fault (SIGSEGV); if this signal is not
     caught by a handler using the signal stack, this signal will kill the process.

     A file I/O operation that would create a file larger that the process' soft limit will cause
     the write to fail and a signal SIGXFSZ to be generated; this normally terminates the
     process, but may be caught.  When the soft cpu time limit is exceeded, a signal SIGXCPU is
     sent to the offending process.

RETURN VALUES
     A 0 return value indicates that the call succeeded, changing or returning the resource
     limit.   A return value of -1 indicates that an error occurred, and an error code is stored
     in the global location errno.

ERRORS
     Getrlimit() and setrlimit() will fail if:

     [EFAULT]		The address specified for rlp is invalid.

     [EPERM]		The limit specified to setrlimit() would have raised the maximum limit
			value, and the caller is not the super-user.

SEE ALSO
     csh(1), sh(1), quota(2), sigaction(2), sigaltstack(2), sysctl(3)

HISTORY
     The getrlimit() function call appeared in 4.2BSD.

4th Berkeley Distribution		   June 4, 1993 		4th Berkeley Distribution
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