4.3BSD - /usr/man/cat2/setrlimit.0

GETRLIMIT(2)                                                      GETRLIMIT(2)


NAME
       getrlimit, setrlimit - control maximum system resource consumption

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

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

       setrlimit(resource, rlp)
       int resource;
       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_CPU       the maximum amount of cpu time (in seconds) to be used
                        by each process.

       RLIMIT_FSIZE     the largest size, in bytes, of any  single  file  that
                        may be created.

       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_STACK     the maximum size, in bytes, of the stack segment for a
                        process; this defines how far a program’s  stack  seg‐
                        ment  may  be  extended.  Stack extension is performed
                        automatically by the system.

       RLIMIT_CORE      the largest size, in bytes, of a core file that may be
                        created.

       RLIMIT_RSS       the maximum size, in bytes, to which a process’s resi‐
                        dent 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 processes that are exceeding their declared resi‐
                        dent set size.

       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 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 {
                   int  rlim_cur; /* current (soft) limit */
                   int  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
       (0x7fffffff).

       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).

       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 that is  too  large  will
       cause  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 VALUE
       A 0 return value indicates that the call succeeded, changing or return‐
       ing 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
       The possible errors are:

       [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), quota(2), sigvec(2), sigstack(2)

BUGS
       There should be limit and unlimit commands in sh(1) as well as in  csh.


4th Berkeley Distribution        May 13, 1986                     GETRLIMIT(2)