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.\" $Id: sysctl.8,v 1.13 1997/08/30 02:28:00 kato Exp $ 34.\" 35.Dd September 23, 1994 36.Dt SYSCTL 8 37.Os 38.Sh NAME 39.Nm sysctl 40.Nd get or set kernel state 41.Sh SYNOPSIS 42.Nm sysctl 43.Op Fl bn 44.Ar name ... 45.Nm sysctl 46.Op Fl bn 47.Fl w 48.Ar name=value ... 49.Nm sysctl 50.Op Fl bn 51.Fl aAX 52.Sh DESCRIPTION 53The 54.Nm 55utility retrieves kernel state and allows processes with 56appropriate privilege to set kernel state. 57The state to be retrieved or set is described using a 58``Management Information Base'' (``MIB'') style name, 59described as a dotted set of components. 60.Pp 61The following options are available: 62.Bl -tag -width indent 63.It Fl a 64List all the currently available string or integer values. 65.It Fl A 66List all the known MIB names including opaques. 67Those with string or integer values will be printed as with the 68.Fl a 69flag; for the opaque values, 70information about the format and the length is printed in addition the first 71few bytes is dumped in hex. 72.It Fl X 73Same as 74.Fl A 75except the entire value of opaque variables is hexdumped. 76.It Fl n 77Specify that the printing of the field name should be 78suppressed and that only its value should be output. 79This flag is useful for setting shell variables. 80For example, to save the pagesize in variable psize, use: 81.Bd -literal -offset indent -compact 82set psize=`sysctl -n hw.pagesize` 83.Ed 84.It Fl b 85Force the value of the variable(s) to be output in raw, binary 86format. No names are printed and no terminating newlines are output. 87This is mostly useful with a single variable. 88.It Fl w Ar name=value ... 89Set the MIB 90.Ar name 91to the new 92.Ar value . 93If just a MIB style 94.Ar name 95is given, 96the corresponding value is retrieved. 97.El 98.Pp 99The information available from 100.Nm 101consists of integers, strings, and opaques. 102.Nm Sysctl 103only knows about a couple of opaque types, and will resort to hexdumps 104for the rest. 105The opaque information is much more useful if retrieved by special 106purpose programs such as 107.Nm ps , 108.Nm systat , 109and 110.Nm netstat . 111.Pp 112The string and integer information is summarized below. 113For a detailed description of these variable see 114.Xr sysctl 3 . 115.Pp 116The changeable column indicates whether a process with appropriate 117privilege can change the value. 118.Bl -column net.inet.ip.forwardingxxxxxx integerxxx 119.It Sy Name Type Changeable 120.It kern.ostype string no 121.It kern.osrelease string no 122.It kern.osrevision integer no 123.It kern.version string no 124.It kern.maxvnodes integer yes 125.It kern.maxproc integer yes 126.It kern.maxprocperuid integer yes 127.It kern.maxfiles integer yes 128.It kern.maxfilesperproc integer yes 129.It kern.argmax integer no 130.It kern.securelevel integer raise only 131.It kern.hostname string yes 132.It kern.hostid integer yes 133.It kern.clockrate struct no 134.It kern.posix1version integer no 135.It kern.ngroups integer no 136.It kern.job_control integer no 137.It kern.saved_ids integer no 138.It kern.boottime struct no 139.It kern.domainname string yes 140.It kern.update integer yes 141.It kern.osreldate string no 142.It kern.bootfile string yes 143.It vm.loadavg struct no 144.It hw.machine string no 145.It hw.model string no 146.It hw.ncpu integer no 147.It hw.byteorder integer no 148.It hw.physmem integer no 149.It hw.usermem integer no 150.It hw.pagesize integer no 151.It hw.floatingpoint integer no 152.It hw.machine_arch string no 153.It machdep.console_device dev_t no 154.It machdep.adjkerntz integer yes 155.It machdep.disable_rtc_set integer yes 156.It user.cs_path string no 157.It user.bc_base_max integer no 158.It user.bc_dim_max integer no 159.It user.bc_scale_max integer no 160.It user.bc_string_max integer no 161.It user.coll_weights_max integer no 162.It user.expr_nest_max integer no 163.It user.line_max integer no 164.It user.re_dup_max integer no 165.It user.posix2_version integer no 166.It user.posix2_c_bind integer no 167.It user.posix2_c_dev integer no 168.It user.posix2_char_term integer no 169.It user.posix2_fort_dev integer no 170.It user.posix2_fort_run integer no 171.It user.posix2_localedef integer no 172.It user.posix2_sw_dev integer no 173.It user.posix2_upe integer no 174.It user.stream_max integer no 175.It user.tzname_max integer no 176.El 177.Sh EXAMPLES 178For example, to retrieve the maximum number of processes allowed 179in the system, one would use the follow request: 180.Bd -literal -offset indent -compact 181sysctl kern.maxproc 182.Ed 183.Pp 184To set the maximum number of processes allowed 185in the system to 1000, one would use the follow request: 186.Bd -literal -offset indent -compact 187sysctl -w kern.maxproc=1000 188.Ed 189.Pp 190Information about the system clock rate may be obtained with: 191.Bd -literal -offset indent -compact 192sysctl kern.clockrate 193.Ed 194.Pp 195Information about the load average history may be obtained with: 196.Bd -literal -offset indent -compact 197sysctl vm.loadavg 198.Ed 199.Pp 200More variables than these exist, and the best and likely only place 201to search for their deeper meaning is undoubtedly the source where 202they are defined. 203.Sh FILES 204.Bl -tag -width <netinet/icmpXvar.h> -compact 205.It Pa <sys/sysctl.h> 206definitions for top level identifiers, second level kernel and hardware 207identifiers, and user level identifiers 208.It Pa <sys/socket.h> 209definitions for second level network identifiers 210.It Pa <sys/gmon.h> 211definitions for third level profiling identifiers 212.It Pa <vm/vm_param.h> 213definitions for second level virtual memory identifiers 214.It Pa <netinet/in.h> 215definitions for third level Internet identifiers and 216fourth level IP identifiers 217.It Pa <netinet/icmp_var.h> 218definitions for fourth level ICMP identifiers 219.It Pa <netinet/udp_var.h> 220definitions for fourth level UDP identifiers 221.El 222.Sh SEE ALSO 223.Xr sysctl 3 224.Sh BUGS 225.Nm Sysctl 226presently exploits an undocumented interface to the kernel 227sysctl facility to traverse the sysctl tree and to retrieve format 228and name information. 229This correct interface is being thought about for the time being. 230.Sh HISTORY 231.Nm Sysctl 232first appeared in 233.Bx 4.4 . 234.Pp 235In 236.Fx 2.2 , 237.Nm 238was significantly remodeled. 239