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