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 bdeNnox 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 d 75Print the description of the variable instead of its value. 76.It Fl e 77Separate the name and the value of the variable(s) with 78.Ql = . 79This is useful for producing output which can be fed back to the 80.Nm 81utility. 82This option is ignored if either 83.Fl N 84or 85.Fl n 86is specified, or a variable is being set. 87.It Fl N 88Show only variable names, not their values. 89This is particularly useful with shells that offer programmable 90completion. 91To enable completion of variable names in 92.Nm zsh , 93use the following code: 94.Bd -literal -offset indent 95listsysctls () { set -A reply $(sysctl -AN ${1%.*}) } 96compctl -K listsysctls sysctl 97.Ed 98.It Fl n 99Show only variable values, not their names. 100This option is useful for setting shell variables. 101For instance, to save the pagesize in variable 102.Va psize , 103use: 104.Pp 105.Dl "set psize=`sysctl -n hw.pagesize`" 106.It Fl o 107Show opaque variables (which are normally suppressed). 108The format and length are printed, as well as a hex dump of the first 109sixteen bytes of the value. 110.It Fl X 111Equivalent to 112.Fl x a 113(for compatibility). 114.It Fl x 115As 116.Fl o , 117but prints a hex dump of the entire value instead of just the first 118few bytes. 119.El 120.Pp 121The information available from 122.Nm 123consists of integers, strings, and opaques. 124.Nm Sysctl 125only knows about a couple of opaque types, and will resort to hexdumps 126for the rest. 127The opaque information is much more useful if retrieved by special 128purpose programs such as 129.Nm ps , systat , 130and 131.Nm netstat . 132.Pp 133The string and integer information is summarized below. 134For a detailed description of these variable see 135.Xr sysctl 3 . 136.Pp 137The changeable column indicates whether a process with appropriate 138privilege can change the value. 139.Bl -column security.bsd.unprivileged_read_msgbuf integerxxx 140.It Sy "Name Type Changeable 141.It "kern.ostype string no 142.It "kern.osrelease string no 143.It "kern.osrevision integer no 144.It "kern.version string no 145.It "kern.maxvnodes integer yes 146.It "kern.maxproc integer no 147.It "kern.maxprocperuid integer yes 148.It "kern.maxfiles integer yes 149.It "kern.maxfilesperproc integer yes 150.It "kern.argmax integer no 151.It "kern.securelevel integer raise only 152.It "kern.hostname string yes 153.It "kern.hostid integer yes 154.It "kern.clockrate struct no 155.It "kern.posix1version integer no 156.It "kern.ngroups integer no 157.It "kern.job_control integer no 158.It "kern.saved_ids integer no 159.It "kern.boottime struct no 160.It "kern.domainname string yes 161.It "kern.filedelay integer yes 162.It "kern.dirdelay integer yes 163.It "kern.metadelay integer yes 164.It "kern.osreldate string no 165.It "kern.bootfile string yes 166.It "kern.corefile string yes 167.It "kern.logsigexit integer yes 168.It "security.bsd.suser_enabled integer yes 169.It "security.bsd.see_other_uids integer yes 170.It "security.bsd.unprivileged_proc_debug integer yes 171.It "security.bsd.unprivileged_read_msgbuf integer yes 172.It "vm.loadavg struct no 173.It "hw.machine string no 174.It "hw.model string no 175.It "hw.ncpu integer no 176.It "hw.byteorder integer no 177.It "hw.physmem integer no 178.It "hw.usermem integer no 179.It "hw.pagesize integer no 180.It "hw.floatingpoint integer no 181.It "hw.machine_arch string no 182.It "machdep.console_device dev_t no 183.It "machdep.adjkerntz integer yes 184.It "machdep.disable_rtc_set integer yes 185.It "user.cs_path string no 186.It "user.bc_base_max integer no 187.It "user.bc_dim_max integer no 188.It "user.bc_scale_max integer no 189.It "user.bc_string_max integer no 190.It "user.coll_weights_max integer no 191.It "user.expr_nest_max integer no 192.It "user.line_max integer no 193.It "user.re_dup_max integer no 194.It "user.posix2_version integer no 195.It "user.posix2_c_bind integer no 196.It "user.posix2_c_dev integer no 197.It "user.posix2_char_term integer no 198.It "user.posix2_fort_dev integer no 199.It "user.posix2_fort_run integer no 200.It "user.posix2_localedef integer no 201.It "user.posix2_sw_dev integer no 202.It "user.posix2_upe integer no 203.It "user.stream_max integer no 204.It "user.tzname_max integer no 205.El 206.Sh EXAMPLES 207For example, to retrieve the maximum number of processes allowed 208in the system, one would use the following request: 209.Pp 210.Dl "sysctl kern.maxproc" 211.Pp 212To set the maximum number of processes allowed 213per uid to 1000, one would use the following request: 214.Pp 215.Dl "sysctl kern.maxprocperuid=1000" 216.Pp 217Information about the system clock rate may be obtained with: 218.Pp 219.Dl "sysctl kern.clockrate" 220.Pp 221Information about the load average history may be obtained with: 222.Pp 223.Dl "sysctl vm.loadavg" 224.Pp 225More variables than these exist, and the best and likely only place 226to search for their deeper meaning is undoubtedly the source where 227they are defined. 228.Sh FILES 229.Bl -tag -width ".Aq Pa netinet/icmp_var.h" -compact 230.It Aq Pa sys/sysctl.h 231definitions for top level identifiers, second level kernel and hardware 232identifiers, and user level identifiers 233.It Aq Pa sys/socket.h 234definitions for second level network identifiers 235.It Aq Pa sys/gmon.h 236definitions for third level profiling identifiers 237.It Aq Pa vm/vm_param.h 238definitions for second level virtual memory identifiers 239.It Aq Pa netinet/in.h 240definitions for third level Internet identifiers and 241fourth level IP identifiers 242.It Aq Pa netinet/icmp_var.h 243definitions for fourth level ICMP identifiers 244.It Aq Pa netinet/udp_var.h 245definitions for fourth level UDP identifiers 246.El 247.Sh COMPATIBILITY 248The 249.Fl w 250option has been deprecated and is silently ignored. 251.Sh SEE ALSO 252.Xr sysctl 3 , 253.Xr sysctl.conf 5 254.Sh BUGS 255.Nm Sysctl 256presently exploits an undocumented interface to the kernel 257sysctl facility to traverse the sysctl tree and to retrieve format 258and name information. 259This correct interface is being thought about for the time being. 260.Sh HISTORY 261.Nm Sysctl 262first appeared in 263.Bx 4.4 . 264.Pp 265In 266.Fx 2.2 , 267.Nm 268was significantly remodeled. 269