.\" $OpenBSD: sysctl.8,v 1.10 1997/07/15 00:38:14 angelos Exp $ .\" $NetBSD: sysctl.8,v 1.4 1995/09/30 07:12:49 thorpej Exp $ .\" .\" Copyright (c) 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)sysctl.8 8.1 (Berkeley) 6/6/93 .\" .Dd June, 6, 1993 .Dt SYSCTL 8 .Os .Sh NAME .Nm sysctl .Nd get or set kernel state .Sh SYNOPSIS .Nm sysctl .Op Fl n .Ar name ... .Nm sysctl .Op Fl n .Fl w .Ar name=value ... .Nm sysctl .Op Fl n .Fl aA .Sh DESCRIPTION The .Nm sysctl utility retrieves kernel state and allows processes with appropriate privilege to set kernel state. The state to be retrieved or set is described using a ``Management Information Base'' (``MIB'') style name, described as a dotted set of components. The .Fl a flag can be used to list all the currently available string or integer values. The .Fl A flag will list all the known MIB names including tables. Those with string or integer values will be printed as with the .Fl a flag; for the table values, the name of the utility to retrieve them is given. .Pp The .Fl n flag specifies that the printing of the field name should be suppressed and that only its value should be output. This flag is useful for setting shell variables. For example, to save the pagesize in variable psize, use: .Bd -literal -offset indent -compact set psize=`sysctl -n hw.pagesize` .Ed .Pp If just a MIB style name is given, the corresponding value is retrieved. If a value is to be set, the .Fl w flag must be specified and the MIB name followed by an equal sign and the new value to be used. .Pp The information available from .Nm sysctl consists of integers, strings, and tables. The tabular information can only be retrieved by special purpose programs such as .Nm ps , .Nm systat , and .Nm netstat . The string and integer information is summaried below. For a detailed description of these variable see .Xr sysctl 3 . The changeable column indicates whether a process with appropriate privilege can change the value. .Bl -column net.inet.ip.forwardingxxxxxx integerxxx .It Sy Name Type Changeable .It kern.ostype string no .It kern.osrelease string no .It kern.osrevision integer no .It kern.osversion string no .It kern.version string no .It kern.maxvnodes integer yes .It kern.maxproc integer yes .It kern.maxfiles integer yes .It kern.maxpartitions integer no .It kern.rawpartition integer no .It kern.argmax integer no .It kern.securelevel integer raise only .It kern.hostname string yes .It kern.domainname string yes .It kern.hostid integer yes .It kern.clockrate struct no .It kern.posix1version integer no .It kern.ngroups integer no .It kern.job_control integer no .It kern.saved_ids integer no .It kern.link_max integer no .It kern.max_canon integer no .It kern.max_input integer no .It kern.name_max integer no .It kern.path_max integer no .It kern.pipe_buf integer no .It kern.chown_restricted integer no .It kern.no_trunc integer no .It kern.vdisable integer no .It kern.boottime struct no .It kern.somaxconn integer yes .It kern.sominconn integer yes .It kern.usermount integer yes .It kern.random struct no .It vm.loadavg struct no .It vm.psstrings struct no .It fs.posix.setuid integer yes .It net.inet.ip.forwarding integer yes .It net.inet.ip.redirect integer yes .It net.inet.ip.ttl integer yes .It net.inet.ip.sourceroute integer yes .It net.inet.ip.directed-broadcast integer yes .It net.inet.ip.portfirst integer yes .It net.inet.ip.portlast integer yes .It net.inet.ip.porthifirst integer yes .It net.inet.ip.porthilast integer yes .It net.inet.ip.portfirst integer yes .It net.inet.icmp.maskrepl integer yes .It net.inet.tcp.rfc1323 integer yes .It net.inet.tcp.keepinittime integer yes .It net.inet.tcp.keepidle integer yes .It net.inet.tcp.keepintvl integer yes .It net.inet.tcp.slowhz integer no .It net.inet.udp.checksum integer yes .It net.ipx.ipx.recvspace integer yes .It net.ipx.ipx.sendspace integer yes .It net.ipsec.encap.encdebug integer yes .It debug.syncprt integer yes .It debug.busyprt integer yes .It debug.doclusterread integer yes .It debug.doclusterwrite integer yes .It debug.doreallocblks integer yes .It debug.doasyncfree integer yes .It debug.prtrealloc integer yes .It hw.machine string no .It hw.model string no .It hw.ncpu integer no .It hw.byteorder integer no .It hw.physmem integer no .It hw.usermem integer no .It hw.pagesize integer no .It machdep.console_device dev_t no .It user.cs_path string no .It user.bc_base_max integer no .It user.bc_dim_max integer no .It user.bc_scale_max integer no .It user.bc_string_max integer no .It user.coll_weights_max integer no .It user.expr_nest_max integer no .It user.line_max integer no .It user.re_dup_max integer no .It user.posix2_version integer no .It user.posix2_c_bind integer no .It user.posix2_c_dev integer no .It user.posix2_char_term integer no .It user.posix2_fort_dev integer no .It user.posix2_fort_run integer no .It user.posix2_localedef integer no .It user.posix2_sw_dev integer no .It user.posix2_upe integer no .It user.stream_max integer no .It user.tzname_max integer no .It ddb.radix integer yes .It ddb.max_width integer yes .It ddb.max_line integer yes .It ddb.tab_stop_width integer yes .El .Sh EXAMPLES .Pp For example, to retrieve the maximum number of processes allowed in the system, one would use the follow request: .Bd -literal -offset indent -compact sysctl kern.maxproc .Ed .Pp To set the maximum number of processes allowed in the system to 1000, one would use the follow request: .Bd -literal -offset indent -compact sysctl -w kern.maxproc=1000 .Ed .Pp Information about the system clock rate may be obtained with: .Bd -literal -offset indent -compact sysctl kern.clockrate .Ed .Pp Information about the load average history may be obtained with .Bd -literal -offset indent -compact sysctl vm.loadavg .Ed .Sh FILES .Bl -tag -width -compact .It Pa definitions for top level identifiers, second level kernel and hardware identifiers, and user level identifiers .It Pa definitions for .Xr random 4 device's statistics structure .It Pa definitions for second level network identifiers .It Pa definitions for third level profiling identifiers .It Pa definitions for second level virtual memory identifiers .It Pa definitions for third level Internet identifiers and fourth level IP identifiers .It Pa definitions for fourth level ICMP identifiers .It Pa definitions for fourth level UDP identifiers .It Pa definitions for third level IPX identifiers and fourth level IPX identifiers .It Pa definitions for second level ddb identifiers .El .Sh SEE ALSO .Xr sysctl 3 .Sh HISTORY .Nm sysctl first appeared in 4.4BSD.