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Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)getrlimit.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/sys/getrlimit.2,v 1.10.2.5 2001/12/14 18:34:00 ru Exp $ 34.\" $DragonFly: src/lib/libc/sys/getrlimit.2,v 1.5 2008/10/17 12:41:38 swildner Exp $ 35.\" 36.Dd July 6, 2009 37.Dt GETRLIMIT 2 38.Os 39.Sh NAME 40.Nm getrlimit , 41.Nm setrlimit 42.Nd control maximum system resource consumption 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In sys/types.h 47.In sys/time.h 48.In sys/resource.h 49.Ft int 50.Fn getrlimit "int resource" "struct rlimit *rlp" 51.Ft int 52.Fn setrlimit "int resource" "const struct rlimit *rlp" 53.Sh DESCRIPTION 54Limits on the consumption of system resources by the current process 55and each process it creates may be obtained with the 56.Fn getrlimit 57call, and set with the 58.Fn setrlimit 59call. 60.Pp 61The 62.Fa resource 63parameter is one of the following: 64.Bl -tag -width RLIMIT_FSIZEAA 65.It Li RLIMIT_AS 66The maximum size (in bytes) of a process' total available memory. 67If this limit is exceeded, the 68.Xr malloc 3 69and 70.Xr mmap 2 71functions will fail and 72.Va errno 73set to 74.Er ENOMEM . 75Moreover, the automatic stack growth will fail as well. 76.It Li RLIMIT_CORE 77The largest size (in bytes) 78.Xr core 5 79file that may be created. 80.It Li RLIMIT_CPU 81The maximum amount of cpu time (in seconds) to be used by 82each process. 83.It Li RLIMIT_DATA 84The maximum size (in bytes) of the data segment for a process; 85this defines how far a program may extend its break with the 86.Xr sbrk 2 87system call. 88.It Li RLIMIT_FSIZE 89The largest size (in bytes) file that may be created. 90.It Li RLIMIT_MEMLOCK 91The maximum size (in bytes) which a process may lock into memory 92using the 93.Xr mlock 2 94function. 95.It Li RLIMIT_NOFILE 96The maximum number of open files for this process. 97.It Li RLIMIT_NPROC 98The maximum number of simultaneous processes for this user id. 99.It Li RLIMIT_RSS 100The maximum size (in bytes) to which a process's resident set size may 101grow. 102This imposes a limit on the amount of physical memory to be given to 103a process; if memory is tight, the system will prefer to take memory 104from processes that are exceeding their declared resident set size. 105.It Li RLIMIT_STACK 106The maximum size (in bytes) of the stack segment for a process; 107this defines how far a program's stack segment may be extended. 108Stack extension is performed automatically by the system. 109.It Li RLIMIT_SBSIZE 110The maximum size (in bytes) of socket buffer usage for this user. 111This limits the amount of network memory, and hence the amount of 112mbufs, that this user may hold at any time. 113.It Li RLIMIT_POSIXLOCK 114The maximum number of POSIX-type advisory-mode locks available to 115this user. 116.El 117.Pp 118A resource limit is specified as a soft limit and a hard limit. 119When a soft limit is exceeded a process may receive a signal (for example, if 120the cpu time or file size is exceeded), but it will be allowed to 121continue execution until it reaches the hard limit (or modifies 122its resource limit). 123The 124.Em rlimit 125structure is used to specify the hard and soft limits on a resource, 126.Bd -literal -offset indent 127struct rlimit { 128 rlim_t rlim_cur; /* current (soft) limit */ 129 rlim_t rlim_max; /* maximum value for rlim_cur */ 130}; 131.Ed 132.Pp 133Only the super-user may raise the maximum limits. 134Other users may only alter 135.Fa rlim_cur 136within the range from 0 to 137.Fa rlim_max 138or (irreversibly) lower 139.Fa rlim_max . 140.Pp 141An 142.Dq infinite 143value for a limit is defined as 144.Dv RLIM_INFINITY . 145.Pp 146Because this information is stored in the per-process information, 147this system call must be executed directly by the shell if it 148is to affect all future processes created by the shell; 149.Ic limit 150is thus a built-in command to 151.Xr csh 1 . 152.Pp 153The system refuses to extend the data or stack space when the limits 154would be exceeded in the normal way: a 155.Xr brk 2 156call fails if the data space limit is reached. 157When the stack limit is reached, the process receives 158a segmentation fault 159.Pq Dv SIGSEGV ; 160if this signal is not 161caught by a handler using the signal stack, this signal 162will kill the process. 163.Pp 164A file I/O operation that would create a file larger than the process' 165soft limit will cause the write to fail and a signal 166.Dv SIGXFSZ 167to be 168generated; this normally terminates the process, but may be caught. 169When the soft cpu time limit is exceeded, a signal 170.Dv SIGXCPU 171is sent to the 172offending process. 173.Sh RETURN VALUES 174.Rv -std 175.Sh ERRORS 176.Fn Getrlimit 177and 178.Fn setrlimit 179will fail if: 180.Bl -tag -width Er 181.It Bq Er EFAULT 182The address specified for 183.Fa rlp 184is invalid. 185.It Bq Er EPERM 186The limit specified to 187.Fn setrlimit 188would have 189raised the maximum limit value, and the caller is not the super-user. 190.El 191.Sh SEE ALSO 192.Xr csh 1 , 193.Xr quota 1 , 194.Xr quotactl 2 , 195.Xr sigaltstack 2 , 196.Xr sigvec 2 , 197.Xr sysctl 3 , 198.Xr ulimit 3 199.Sh HISTORY 200The 201.Fn getrlimit 202function call appeared in 203.Bx 4.2 . 204