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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 1.4 2004/06/06 13:33:28 hmp Exp $ 35.\" 36.Dd June 4, 1993 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_CORE 66The largest size (in bytes) 67.Xr core 5 68file that may be created. 69.It Li RLIMIT_CPU 70The maximum amount of cpu time (in seconds) to be used by 71each process. 72.It Li RLIMIT_DATA 73The maximum size (in bytes) of the data segment for a process; 74this defines how far a program may extend its break with the 75.Xr sbrk 2 76system call. 77.It Li RLIMIT_FSIZE 78The largest size (in bytes) file that may be created. 79.It Li RLIMIT_MEMLOCK 80The maximum size (in bytes) which a process may lock into memory 81using the 82.Xr mlock 2 83function. 84.It Li RLIMIT_NOFILE 85The maximum number of open files for this process. 86.It Li RLIMIT_NPROC 87The maximum number of simultaneous processes for this user id. 88.It Li RLIMIT_RSS 89The maximum size (in bytes) to which a process's resident set size may 90grow. 91This imposes a limit on the amount of physical memory to be given to 92a process; if memory is tight, the system will prefer to take memory 93from processes that are exceeding their declared resident set size. 94.It Li RLIMIT_STACK 95The maximum size (in bytes) of the stack segment for a process; 96this defines how far a program's stack segment may be extended. 97Stack extension is performed automatically by the system. 98.It Li RLIMIT_SBSIZE 99The maximum size (in bytes) of socket buffer usage for this user. 100This limits the amount of network memory, and hence the amount of 101mbufs, that this user may hold at any time. 102.It Li RLIMIT_POSIXLOCK 103The maximum number of POSIX-type advisory-mode locks available to 104this user. 105.El 106.Pp 107A resource limit is specified as a soft limit and a hard limit. When a 108soft limit is exceeded a process may receive a signal (for example, if 109the cpu time or file size is exceeded), but it will be allowed to 110continue execution until it reaches the hard limit (or modifies 111its resource limit). The 112.Em rlimit 113structure is used to specify the hard and soft limits on a resource, 114.Bd -literal -offset indent 115struct rlimit { 116 rlim_t rlim_cur; /* current (soft) limit */ 117 rlim_t rlim_max; /* maximum value for rlim_cur */ 118}; 119.Ed 120.Pp 121Only the super-user may raise the maximum limits. Other users 122may only alter 123.Fa rlim_cur 124within the range from 0 to 125.Fa rlim_max 126or (irreversibly) lower 127.Fa rlim_max . 128.Pp 129An 130.Dq infinite 131value for a limit is defined as 132.Dv RLIM_INFINITY . 133.Pp 134Because this information is stored in the per-process information, 135this system call must be executed directly by the shell if it 136is to affect all future processes created by the shell; 137.Ic limit 138is thus a built-in command to 139.Xr csh 1 . 140.Pp 141The system refuses to extend the data or stack space when the limits 142would be exceeded in the normal way: a 143.Xr brk 2 144call fails if the data space limit is reached. 145When the stack limit is reached, the process receives 146a segmentation fault 147.Pq Dv SIGSEGV ; 148if this signal is not 149caught by a handler using the signal stack, this signal 150will kill the process. 151.Pp 152A file I/O operation that would create a file larger that the process' 153soft limit will cause the write to fail and a signal 154.Dv SIGXFSZ 155to be 156generated; this normally terminates the process, but may be caught. When 157the soft cpu time limit is exceeded, a signal 158.Dv SIGXCPU 159is sent to the 160offending process. 161.Sh RETURN VALUES 162.Rv -std 163.Sh ERRORS 164.Fn Getrlimit 165and 166.Fn setrlimit 167will fail if: 168.Bl -tag -width Er 169.It Bq Er EFAULT 170The address specified for 171.Fa rlp 172is invalid. 173.It Bq Er EPERM 174The limit specified to 175.Fn setrlimit 176would have 177raised the maximum limit value, and the caller is not the super-user. 178.El 179.Sh SEE ALSO 180.Xr csh 1 , 181.Xr quota 1 , 182.Xr quotactl 2 , 183.Xr sigaltstack 2 , 184.Xr sigvec 2 , 185.Xr sysctl 3 , 186.Xr ulimit 3 187.Sh HISTORY 188The 189.Fn getrlimit 190function call appeared in 191.Bx 4.2 . 192