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.\" From: @(#)sysctl.8 8.1 (Berkeley) 6/6/93 33.\" $FreeBSD$ 34.\" 35.Dd May 28, 2001 36.Dt SYSCTL 8 37.Os 38.Sh NAME 39.Nm sysctl 40.Nd get or set kernel state 41.Sh SYNOPSIS 42.Nm 43.Op Fl beNnox 44.Ar name Ns Op = Ns Ar value 45.Ar ... 46.Nm 47.Op Fl beNnox 48.Fl a 49.Sh DESCRIPTION 50The 51.Nm 52utility retrieves kernel state and allows processes with appropriate 53privilege to set kernel state. 54The state to be retrieved or set is described using a 55.Dq Management Information Base 56.Pq Dq MIB 57style name, described as a dotted set of 58components. 59.Pp 60The following options are available: 61.Bl -tag -width indent 62.It Fl A 63Equivalent to 64.Fl o a 65(for compatibility). 66.It Fl a 67List all the currently available non-opaque values. 68This option is ignored if one or more variable names are specified on 69the command line. 70.It Fl b 71Force the value of the variable(s) to be output in raw, binary format. 72No names are printed and no terminating newlines are output. 73This is mostly useful with a single variable. 74.It Fl e 75Separate the name and the value of the variable(s) with 76.Ql = . 77This is useful for producing output which can be fed back to the 78.Nm 79utility. 80This option is ignored if either 81.Fl N 82or 83.Fl n 84is specified, or a variable is being set. 85.It Fl N 86Show only variable names, not their values. 87This is particularly useful with shells that offer programmable 88completion. 89To enable completion of variable names in 90.Nm zsh , 91use the following code: 92.Bd -literal -offset indent 93listsysctls () { set -A reply $(sysctl -AN ${1%.*}) } 94compctl -K listsysctls sysctl 95.Ed 96.It Fl n 97Show only variable values, not their names. 98This option is useful for setting shell variables. 99For instance, to save the pagesize in variable 100.Va psize , 101use: 102.Pp 103.Dl "set psize=`sysctl -n hw.pagesize`" 104.It Fl o 105Show opaque variables (which are normally suppressed). 106The format and length are printed, as well as a hex dump of the first 107sixteen bytes of the value. 108.It Fl X 109Equivalent to 110.Fl x a 111(for compatibility). 112.It Fl x 113As 114.Fl o , 115but prints a hex dump of the entire value instead of just the first 116few bytes. 117.El 118.Pp 119The information available from 120.Nm 121consists of integers, strings, and opaques. 122.Nm Sysctl 123only knows about a couple of opaque types, and will resort to hexdumps 124for the rest. 125The opaque information is much more useful if retrieved by special 126purpose programs such as 127.Nm ps , systat , 128and 129.Nm netstat . 130.Pp 131The string and integer information is summarized below. 132For a detailed description of these variable see 133.Xr sysctl 3 . 134.Pp 135The changeable column indicates whether a process with appropriate 136privilege can change the value. 137.Bl -column net.inet.ip.forwardingxxxxxx integerxxx 138.It Sy "Name Type Changeable 139.It "kern.ostype string no 140.It "kern.osrelease string no 141.It "kern.osrevision integer no 142.It "kern.version string no 143.It "kern.maxvnodes integer yes 144.It "kern.maxproc integer no 145.It "kern.maxprocperuid integer yes 146.It "kern.maxfiles integer yes 147.It "kern.maxfilesperproc integer yes 148.It "kern.argmax integer no 149.It "kern.suser_permitted integer yes 150.It "kern.securelevel integer raise only 151.It "kern.hostname string yes 152.It "kern.hostid integer yes 153.It "kern.clockrate struct no 154.It "kern.posix1version integer no 155.It "kern.ngroups integer no 156.It "kern.job_control integer no 157.It "kern.saved_ids integer no 158.It "kern.boottime struct no 159.It "kern.domainname string yes 160.It "kern.filedelay integer yes 161.It "kern.dirdelay integer yes 162.It "kern.metadelay integer yes 163.It "kern.osreldate string no 164.It "kern.bootfile string yes 165.It "kern.corefile string yes 166.It "kern.logsigexit integer yes 167.It "vm.loadavg struct no 168.It "hw.machine string no 169.It "hw.model string no 170.It "hw.ncpu integer no 171.It "hw.byteorder integer no 172.It "hw.physmem integer no 173.It "hw.usermem integer no 174.It "hw.pagesize integer no 175.It "hw.floatingpoint integer no 176.It "hw.machine_arch string no 177.It "machdep.console_device dev_t no 178.It "machdep.adjkerntz integer yes 179.It "machdep.disable_rtc_set integer yes 180.It "user.cs_path string no 181.It "user.bc_base_max integer no 182.It "user.bc_dim_max integer no 183.It "user.bc_scale_max integer no 184.It "user.bc_string_max integer no 185.It "user.coll_weights_max integer no 186.It "user.expr_nest_max integer no 187.It "user.line_max integer no 188.It "user.re_dup_max integer no 189.It "user.posix2_version integer no 190.It "user.posix2_c_bind integer no 191.It "user.posix2_c_dev integer no 192.It "user.posix2_char_term integer no 193.It "user.posix2_fort_dev integer no 194.It "user.posix2_fort_run integer no 195.It "user.posix2_localedef integer no 196.It "user.posix2_sw_dev integer no 197.It "user.posix2_upe integer no 198.It "user.stream_max integer no 199.It "user.tzname_max integer no 200.El 201.Sh EXAMPLES 202For example, to retrieve the maximum number of processes allowed 203in the system, one would use the following request: 204.Pp 205.Dl "sysctl kern.maxproc" 206.Pp 207To set the maximum number of processes allowed 208per uid to 1000, one would use the following request: 209.Pp 210.Dl "sysctl kern.maxprocperuid=1000" 211.Pp 212Information about the system clock rate may be obtained with: 213.Pp 214.Dl "sysctl kern.clockrate" 215.Pp 216Information about the load average history may be obtained with: 217.Pp 218.Dl "sysctl vm.loadavg" 219.Pp 220More variables than these exist, and the best and likely only place 221to search for their deeper meaning is undoubtedly the source where 222they are defined. 223.Sh FILES 224.Bl -tag -width ".Aq Pa netinet/icmp_var.h" -compact 225.It Aq Pa sys/sysctl.h 226definitions for top level identifiers, second level kernel and hardware 227identifiers, and user level identifiers 228.It Aq Pa sys/socket.h 229definitions for second level network identifiers 230.It Aq Pa sys/gmon.h 231definitions for third level profiling identifiers 232.It Aq Pa vm/vm_param.h 233definitions for second level virtual memory identifiers 234.It Aq Pa netinet/in.h 235definitions for third level Internet identifiers and 236fourth level IP identifiers 237.It Aq Pa netinet/icmp_var.h 238definitions for fourth level ICMP identifiers 239.It Aq Pa netinet/udp_var.h 240definitions for fourth level UDP identifiers 241.El 242.Sh COMPATIBILITY 243The 244.Fl w 245option has been deprecated and is silently ignored. 246.Sh SEE ALSO 247.Xr sysctl 3 , 248.Xr sysctl.conf 5 249.Sh BUGS 250.Nm Sysctl 251presently exploits an undocumented interface to the kernel 252sysctl facility to traverse the sysctl tree and to retrieve format 253and name information. 254This correct interface is being thought about for the time being. 255.Sh HISTORY 256.Nm Sysctl 257first appeared in 258.Bx 4.4 . 259.Pp 260In 261.Fx 2.2 , 262.Nm 263was significantly remodeled. 264