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IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)getrlimit.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD: src/lib/libc/sys/getrlimit.2,v 1.10.2.5 2001/12/14 18:34:00 ru Exp $ 30.\" 31.Dd July 6, 2009 32.Dt GETRLIMIT 2 33.Os 34.Sh NAME 35.Nm getrlimit , 36.Nm setrlimit 37.Nd control maximum system resource consumption 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In sys/types.h 42.In sys/time.h 43.In sys/resource.h 44.Ft int 45.Fn getrlimit "int resource" "struct rlimit *rlp" 46.Ft int 47.Fn setrlimit "int resource" "const struct rlimit *rlp" 48.Sh DESCRIPTION 49Limits on the consumption of system resources by the current process 50and each process it creates may be obtained with the 51.Fn getrlimit 52call, and set with the 53.Fn setrlimit 54call. 55.Pp 56The 57.Fa resource 58parameter is one of the following: 59.Bl -tag -width ".Dv RLIMIT_POSIXLOCKS" 60.It Dv RLIMIT_AS 61The maximum size (in bytes) of a process' total available memory. 62If this limit is exceeded, the 63.Xr malloc 3 64and 65.Xr mmap 2 66functions will fail and 67.Va errno 68set to 69.Er ENOMEM . 70Moreover, the automatic stack growth will fail as well. 71.It Dv RLIMIT_CORE 72The largest size (in bytes) 73.Xr core 5 74file that may be created. 75.It Dv RLIMIT_CPU 76The maximum amount of cpu time (in seconds) to be used by 77each process. 78.It Dv RLIMIT_DATA 79The maximum size (in bytes) of the data segment for a process; 80this defines how far a program may extend its break with the 81.Xr sbrk 2 82system call. 83.It Dv RLIMIT_FSIZE 84The largest size (in bytes) file that may be created. 85.It Dv RLIMIT_MEMLOCK 86The maximum size (in bytes) which a process may lock into memory 87using the 88.Xr mlock 2 89function. 90.It Dv RLIMIT_NOFILE 91The maximum number of open files for this process. 92.It Dv RLIMIT_NPROC 93The maximum number of simultaneous processes for this user id. 94.It Dv RLIMIT_RSS 95The maximum size (in bytes) to which a process's resident set size may 96grow. 97This imposes a limit on the amount of physical memory to be given to 98a process; if memory is tight, the system will prefer to take memory 99from processes that are exceeding their declared resident set size. 100.It Dv RLIMIT_STACK 101The maximum size (in bytes) of the stack segment for a process; 102this defines how far a program's stack segment may be extended. 103Stack extension is performed automatically by the system. 104.It Dv RLIMIT_SBSIZE 105The maximum size (in bytes) of socket buffer usage for this user. 106This limits the amount of network memory, and hence the amount of 107mbufs, that this user may hold at any time. 108.It Dv RLIMIT_POSIXLOCKS 109The maximum number of POSIX-type advisory-mode locks available to 110this user. 111.El 112.Pp 113A resource limit is specified as a soft limit and a hard limit. 114When a soft limit is exceeded a process may receive a signal (for example, if 115the cpu time or file size is exceeded), but it will be allowed to 116continue execution until it reaches the hard limit (or modifies 117its resource limit). 118The 119.Em rlimit 120structure is used to specify the hard and soft limits on a resource, 121.Bd -literal -offset indent 122struct rlimit { 123 rlim_t rlim_cur; /* current (soft) limit */ 124 rlim_t rlim_max; /* maximum value for rlim_cur */ 125}; 126.Ed 127.Pp 128Only the super-user may raise the maximum limits. 129Other users may only alter 130.Fa rlim_cur 131within the range from 0 to 132.Fa rlim_max 133or (irreversibly) lower 134.Fa rlim_max . 135.Pp 136An 137.Dq infinite 138value for a limit is defined as 139.Dv RLIM_INFINITY . 140.Pp 141Because this information is stored in the per-process information, 142this system call must be executed directly by the shell if it 143is to affect all future processes created by the shell; 144.Ic limit 145is thus a built-in command to 146.Xr csh 1 . 147.Pp 148The system refuses to extend the data or stack space when the limits 149would be exceeded in the normal way: a 150.Xr brk 2 151call fails if the data space limit is reached. 152When the stack limit is reached, the process receives 153a segmentation fault 154.Pq Dv SIGSEGV ; 155if this signal is not 156caught by a handler using the signal stack, this signal 157will kill the process. 158.Pp 159A file I/O operation that would create a file larger than the process' 160soft limit will cause the write to fail and a signal 161.Dv SIGXFSZ 162to be 163generated; this normally terminates the process, but may be caught. 164When the soft cpu time limit is exceeded, a signal 165.Dv SIGXCPU 166is sent to the 167offending process. 168.Sh RETURN VALUES 169.Rv -std 170.Sh ERRORS 171.Fn Getrlimit 172and 173.Fn setrlimit 174will fail if: 175.Bl -tag -width Er 176.It Bq Er EFAULT 177The address specified for 178.Fa rlp 179is invalid. 180.It Bq Er EPERM 181The limit specified to 182.Fn setrlimit 183would have 184raised the maximum limit value, and the caller is not the super-user. 185.El 186.Sh SEE ALSO 187.Xr csh 1 , 188.Xr quota 1 , 189.Xr quotactl 2 , 190.Xr sigaction 2 , 191.Xr sigaltstack 2 , 192.Xr sysctl 3 , 193.Xr ulimit 3 194.Sh HISTORY 195The 196.Fn getrlimit 197function call appeared in 198.Bx 4.2 . 199