1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. 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.\" @(#)sysctl.8 8.1 (Berkeley) 6/6/93 33.\" 34.Dd "June 6, 1993" 35.Dt SYSCTL 8 36.Os 37.Sh NAME 38.Nm sysctl 39.Nd get or set kernel state 40.Sh SYNOPSIS 41.Nm sysctl 42.Op Fl n 43.Ar name ... 44.Nm sysctl 45.Op Fl n 46.Fl w 47.Ar name=value ... 48.Nm sysctl 49.Op Fl n 50.Fl aA 51.Sh DESCRIPTION 52The 53.Nm sysctl 54utility retrieves kernel state and allows processes with 55appropriate privilege to set kernel state. 56The state to be retrieved or set is described using a 57``Management Information Base'' (``MIB'') style name, 58described as a dotted set of components. 59The 60.Fl a 61flag can be used to list all the currently available string or integer values. 62The 63.Fl A 64flag will list all the known MIB names including tables. 65Those with string or integer values will be printed as with the 66.Fl a 67flag; for the table values, 68the name of the utility to retrieve them is given. 69.Pp 70The 71.Fl n 72flag specifies that the printing of the field name should be 73suppressed and that only its value should be output. 74This flag is useful for setting shell variables. 75For example, to save the pagesize in variable psize, use: 76.Bd -literal -offset indent -compact 77set psize=`sysctl -n hw.pagesize` 78.Ed 79.Pp 80If just a MIB style name is given, 81the corresponding value is retrieved. 82If a value is to be set, the 83.Fl w 84flag must be specified and the MIB name followed 85by an equal sign and the new value to be used. 86.Pp 87The information available from 88.Nm sysctl 89consists of integers, strings, and tables. 90The tabular information can only be retrieved by special 91purpose programs such as 92.Nm ps , 93.Nm systat , 94and 95.Nm netstat . 96The string and integer information is summaried below. 97For a detailed description of these variable see 98.Xr sysctl 3 . 99The changeable column indicates whether a process with appropriate 100privilege can change the value. 101.Bl -column net.inet.ip.forwardingxxxxxx integerxxx 102.It Sy Name Type Changeable 103.It kern.ostype string no 104.It kern.osrelease string no 105.It kern.osrevision integer no 106.It kern.version string no 107.It kern.maxvnodes integer yes 108.It kern.maxproc integer yes 109.It kern.maxfiles integer yes 110.It kern.argmax integer no 111.It kern.securelevel integer raise only 112.It kern.hostname string yes 113.It kern.hostid integer yes 114.It kern.clockrate struct no 115.It kern.posix1version integer no 116.It kern.ngroups integer no 117.It kern.job_control integer no 118.It kern.saved_ids integer no 119.It kern.link_max integer no 120.It kern.max_canon integer no 121.It kern.max_input integer no 122.It kern.name_max integer no 123.It kern.path_max integer no 124.It kern.pipe_buf integer no 125.It kern.chown_restricted integer no 126.It kern.no_trunc integer no 127.It kern.vdisable integer no 128.It kern.boottime struct no 129.It vm.loadavg struct no 130.It machdep.console_device dev_t no 131.It net.inet.ip.forwarding integer yes 132.It net.inet.ip.redirect integer yes 133.It net.inet.ip.ttl integer yes 134.It net.inet.icmp.maskrepl integer yes 135.It net.inet.udp.checksum integer yes 136.It hw.machine string no 137.It hw.model string no 138.It hw.ncpu integer no 139.It hw.byteorder integer no 140.It hw.physmem integer no 141.It hw.usermem integer no 142.It hw.pagesize integer no 143.It user.cs_path string no 144.It user.bc_base_max integer no 145.It user.bc_dim_max integer no 146.It user.bc_scale_max integer no 147.It user.bc_string_max integer no 148.It user.coll_weights_max integer no 149.It user.expr_nest_max integer no 150.It user.line_max integer no 151.It user.re_dup_max integer no 152.It user.posix2_version integer no 153.It user.posix2_c_bind integer no 154.It user.posix2_c_dev integer no 155.It user.posix2_char_term integer no 156.It user.posix2_fort_dev integer no 157.It user.posix2_fort_run integer no 158.It user.posix2_localedef integer no 159.It user.posix2_sw_dev integer no 160.It user.posix2_upe integer no 161.El 162.Sh EXAMPLES 163.Pp 164For example, to retrieve the maximum number of processes allowed 165in the system, one would use the follow request: 166.Bd -literal -offset indent -compact 167sysctl kern.maxproc 168.Ed 169.Pp 170To set the maximum number of processes allowed 171in the system to 1000, one would use the follow request: 172.Bd -literal -offset indent -compact 173sysctl -w kern.maxproc=1000 174.Ed 175.Pp 176Information about the system clock rate may be obtained with: 177.Bd -literal -offset indent -compact 178sysctl kern.clockrate 179.Ed 180.Pp 181Information about the load average history may be obtained with 182.Bd -literal -offset indent -compact 183sysctl vm.loadavg 184.Ed 185.Sh FILES 186.Bl -tag -width <netinet/icmpXvar.h> -compact 187.It Pa <sys/sysctl.h> 188definitions for top level identifiers, second level kernel and hardware 189identifiers, and user level identifiers 190.It Pa <sys/socket.h> 191definitions for second level network identifiers 192.It Pa <sys/gmon.h> 193definitions for third level profiling identifiers 194.It Pa <vm/vm_param.h> 195definitions for second level virtual memory identifiers 196.It Pa <netinet/in.h> 197definitions for third level Internet identifiers and 198fourth level IP identifiers 199.It Pa <netinet/icmp_var.h> 200definitions for fourth level ICMP identifiers 201.It Pa <netinet/udp_var.h> 202definitions for fourth level UDP identifiers 203.El 204.Sh SEE ALSO 205.Xr sysctl 3 206.Sh HISTORY 207.Nm sysctl 208first appeared in 4.4BSD. 209