1.\" $OpenBSD: sysctl.8,v 1.182 2014/07/11 16:43:07 henning Exp $ 2.\" $NetBSD: sysctl.8,v 1.4 1995/09/30 07:12:49 thorpej Exp $ 3.\" 4.\" Copyright (c) 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)sysctl.8 8.2 (Berkeley) 5/9/95 32.\" 33.Dd $Mdocdate: July 11 2014 $ 34.Dt SYSCTL 8 35.Os 36.Sh NAME 37.Nm sysctl 38.Nd get or set kernel state 39.Sh SYNOPSIS 40.Nm sysctl 41.Op Fl Aan 42.Nm sysctl 43.Op Fl n 44.Ar name ... 45.Nm sysctl 46.Op Fl nq 47.Ar name Ns = Ns Ar value ... 48.Sh DESCRIPTION 49The 50.Nm 51utility retrieves kernel state and allows processes with 52appropriate privilege to set kernel state. 53The state to be retrieved or set is described using a 54.Dq Management Information Base 55.Pq MIB 56style name, described as a dotted set of components. 57.Pp 58When retrieving a variable, 59a subset of the MIB name may be specified to retrieve a list of 60variables in that subset. 61For example, to list all the machdep variables: 62.Pp 63.Dl $ sysctl machdep 64.Pp 65When setting a variable, 66the MIB name should be followed by an equal sign and the new value. 67.Pp 68The options are as follows: 69.Bl -tag -width xxx 70.It Fl A 71List all the known MIB names including tables. 72Those with string or integer values will be printed as with the 73.Fl a 74flag; for the table values, the name of the utility to retrieve them is given. 75.It Fl a 76List all the currently available string or integer values. 77This is the default, if no parameters are given to 78.Nm . 79.It Fl n 80Suppress printing of the field name, only output the field value. 81Useful for setting shell variables. 82For example, to set the psize shell variable to the pagesize of the hardware: 83.Pp 84.Dl # set psize=`sysctl -n hw.pagesize` 85.It Fl q 86Suppress all output when setting a variable. 87This option overrides the behaviour of 88.Fl n . 89.It Ar name Ns = Ns Ar value 90Attempt to set the specified variable 91.Ar name 92to 93.Ar value . 94.El 95.Pp 96The information available from 97.Nm 98consists of integers, strings, and tables. 99The tabular information can only be retrieved by special 100purpose programs such as 101.Xr ps 1 , 102.Xr systat 1 , 103and 104.Xr netstat 1 . 105The string and integer information is summarized below. 106For a detailed description of these variables, see 107.Xr sysctl 3 . 108The changeable column indicates whether a process with appropriate 109privilege can change the value. 110.Pp 111Note: 112not all of the variables are relevant to all architectures, 113and a few require a kernel compiled with non-standard 114.Xr options 4 . 115.Bl -column "kern.timecounter.timestepwarnings" "integer" "Changeable" 116.It Sy Name Ta Sy Type Ta Sy Changeable 117.It kern.ostype string no 118.It kern.osrelease Ta string Ta no 119.It kern.osrevision Ta integer Ta no 120.It kern.version Ta string Ta no 121.It kern.maxvnodes Ta integer Ta yes 122.It kern.maxproc Ta integer Ta yes 123.It kern.maxfiles Ta integer Ta yes 124.It kern.argmax Ta integer Ta no 125.It kern.securelevel Ta integer Ta raise only 126.It kern.hostname Ta string Ta yes 127.It kern.hostid Ta u_int Ta yes 128.It kern.clockrate Ta struct Ta no 129.It kern.posix1version Ta integer Ta no 130.It kern.ngroups Ta integer Ta no 131.It kern.job_control Ta integer Ta no 132.It kern.saved_ids Ta integer Ta no 133.It kern.boottime Ta struct Ta no 134.It kern.domainname Ta string Ta yes 135.It kern.maxpartitions Ta integer Ta no 136.It kern.rawpartition Ta integer Ta no 137.It kern.maxthread Ta integer Ta yes 138.It kern.nthreads Ta integer Ta no 139.It kern.osversion Ta string Ta no 140.It kern.somaxconn Ta integer Ta yes 141.It kern.sominconn Ta integer Ta yes 142.It kern.usermount Ta integer Ta yes 143.It kern.random Ta struct Ta no 144.It kern.nosuidcoredump Ta integer Ta yes 145.It kern.fsync Ta integer Ta no 146.It kern.sysvmsg Ta integer Ta no 147.It kern.sysvsem Ta integer Ta no 148.It kern.sysvshm Ta integer Ta no 149.It kern.arandom Ta u_int Ta no 150.It kern.msgbufsize Ta integer Ta no 151.It kern.malloc.buckets Ta string Ta no 152.It kern.malloc.bucket.<sz> Ta string Ta no 153.It kern.malloc.kmemnames Ta string Ta no 154.It kern.malloc.kmemstat.<name> Ta string Ta no 155.It kern.cp_time Ta struct Ta no 156.It kern.nchstats Ta struct Ta no 157.It kern.forkstat Ta struct Ta no 158.It kern.nselcoll Ta integer Ta no 159.It kern.tty.tk_nin Ta int64_t Ta no 160.It kern.tty.tk_nout Ta int64_t Ta no 161.It kern.tty.tk_rawcc Ta int64_t Ta no 162.It kern.tty.tk_cancc Ta int64_t Ta no 163.It kern.tty.ttyinfo Ta struct Ta no 164.It kern.tty.maxptys Ta integer Ta yes 165.It kern.tty.nptys Ta integer Ta no 166.It kern.ccpu Ta u_int Ta no 167.It kern.fscale Ta integer Ta no 168.It kern.nprocs Ta integer Ta no 169.It kern.stackgap_random Ta integer Ta yes 170.It kern.usercrypto Ta integer Ta yes 171.It kern.cryptodevallowsoft Ta integer Ta yes 172.It kern.splassert Ta integer Ta yes 173.It kern.nfiles Ta integer Ta no 174.It kern.ttycount Ta integer Ta no 175.It kern.numvnodes Ta integer Ta no 176.It kern.userasymcrypto Ta integer Ta yes 177.It kern.seminfo.semmni Ta integer Ta yes 178.It kern.seminfo.semmns Ta integer Ta yes 179.It kern.seminfo.semmnu Ta integer Ta yes 180.It kern.seminfo.semmsl Ta integer Ta yes 181.It kern.seminfo.semopm Ta integer Ta yes 182.It kern.seminfo.semume Ta integer Ta no 183.It kern.seminfo.semusz Ta integer Ta no 184.It kern.seminfo.semvmx Ta integer Ta no 185.It kern.seminfo.semaem Ta integer Ta no 186.It kern.shminfo.shmmax Ta integer Ta yes 187.It kern.shminfo.shmmin Ta integer Ta yes 188.It kern.shminfo.shmmni Ta integer Ta yes 189.It kern.shminfo.shmseg Ta integer Ta yes 190.It kern.shminfo.shmall Ta integer Ta yes 191.It kern.watchdog.period Ta integer Ta yes 192.It kern.watchdog.auto Ta integer Ta yes 193.It kern.emul.nemuls Ta integer Ta no 194.It kern.emul.other Ta integer Ta yes 195.It kern.maxclusters Ta integer Ta yes 196.It kern.timecounter.tick Ta integer Ta no 197.It kern.timecounter.timestepwarnings Ta integer Ta yes 198.It kern.timecounter.hardware Ta string Ta yes 199.It kern.timecounter.choice Ta string Ta no 200.It kern.maxlocksperuid Ta integer Ta yes 201.It kern.bufcachepercent Ta integer Ta yes 202.It kern.consdev Ta string Ta no 203.It vm.vmmeter Ta struct Ta no 204.It vm.loadavg Ta struct Ta no 205.It vm.psstrings Ta struct Ta no 206.It vm.uvmexp Ta struct Ta no 207.It vm.swapencrypt.enable Ta integer Ta yes 208.It vm.swapencrypt.keyscreated Ta integer Ta no 209.It vm.swapencrypt.keysdeleted Ta integer Ta no 210.It vm.nkmempages Ta integer Ta no 211.It vm.anonmin Ta integer Ta yes 212.It vm.vtextmin Ta integer Ta yes 213.It vm.vnodemin Ta integer Ta yes 214.It vm.maxslp Ta integer Ta no 215.It vm.uspace Ta integer Ta no 216.It fs.posix.setuid Ta integer Ta yes 217.It net.inet.divert.recvspace Ta integer Ta yes 218.It net.inet.divert.sendspace Ta integer Ta yes 219.It net.inet.ip.forwarding Ta integer Ta yes 220.It net.inet.ip.redirect Ta integer Ta yes 221.It net.inet.ip.ttl Ta integer Ta yes 222.\" .It net.inet.ip.mtu Ta integer Ta yes 223.It net.inet.ip.sourceroute Ta integer Ta yes 224.It net.inet.ip.directed-broadcast Ta integer Ta yes 225.It net.inet.ip.portfirst Ta integer Ta yes 226.It net.inet.ip.portlast Ta integer Ta yes 227.It net.inet.ip.porthifirst Ta integer Ta yes 228.It net.inet.ip.porthilast Ta integer Ta yes 229.It net.inet.ip.maxqueue Ta integer Ta yes 230.It net.inet.ip.encdebug Ta integer Ta yes 231.It net.inet.ip.ipsec-expire-acquire Ta integer Ta yes 232.It net.inet.ip.ipsec-invalid-life Ta integer Ta yes 233.It net.inet.ip.ipsec-pfs Ta integer Ta yes 234.It net.inet.ip.ipsec-soft-allocs Ta integer Ta yes 235.It net.inet.ip.ipsec-allocs Ta integer Ta yes 236.It net.inet.ip.ipsec-soft-bytes Ta integer Ta yes 237.It net.inet.ip.ipsec-bytes Ta integer Ta yes 238.It net.inet.ip.ipsec-timeout Ta integer Ta yes 239.It net.inet.ip.ipsec-soft-timeout Ta integer Ta yes 240.It net.inet.ip.ipsec-soft-firstuse Ta integer Ta yes 241.It net.inet.ip.ipsec-firstuse Ta integer Ta yes 242.It net.inet.ip.ipsec-enc-alg Ta string Ta yes 243.It net.inet.ip.ipsec-auth-alg Ta string Ta yes 244.It net.inet.ip.mtudisc Ta integer Ta yes 245.It net.inet.ip.mtudisctimeout Ta integer Ta yes 246.It net.inet.ip.ipsec-comp-alg Ta string Ta yes 247.It net.inet.ip.ifq.len Ta integer Ta no 248.It net.inet.ip.ifq.maxlen Ta integer Ta yes 249.It net.inet.ip.ifq.drops Ta integer Ta no 250.It net.inet.ip.mforwarding Ta integer Ta yes 251.It net.inet.ip.multipath Ta integer Ta yes 252.It net.inet.icmp.maskrepl Ta integer Ta yes 253.It net.inet.icmp.bmcastecho Ta integer Ta yes 254.It net.inet.icmp.errppslimit Ta integer Ta yes 255.It net.inet.icmp.rediraccept Ta integer Ta yes 256.It net.inet.icmp.redirtimeout Ta integer Ta yes 257.It net.inet.icmp.tstamprepl Ta integer Ta yes 258.It net.inet.ipip.allow Ta integer Ta yes 259.It net.inet.tcp.rfc1323 Ta integer Ta yes 260.It net.inet.tcp.keepinittime Ta integer Ta yes 261.It net.inet.tcp.keepidle Ta integer Ta yes 262.It net.inet.tcp.keepintvl Ta integer Ta yes 263.It net.inet.tcp.always_keepalive Ta integer Ta yes 264.It net.inet.tcp.slowhz Ta integer Ta no 265.It net.inet.tcp.baddynamic Ta array Ta yes 266.It net.inet.tcp.sack Ta integer Ta yes 267.It net.inet.tcp.mssdflt Ta integer Ta yes 268.It net.inet.tcp.rstppslimit Ta integer Ta yes 269.It net.inet.tcp.ackonpush Ta integer Ta yes 270.It net.inet.tcp.ecn Ta integer Ta yes 271.It net.inet.tcp.syncachelimit Ta integer Ta yes 272.It net.inet.tcp.synbucketlimit Ta integer Ta yes 273.It net.inet.tcp.rfc3390 Ta integer Ta yes 274.It net.inet.tcp.reasslimit Ta integer Ta yes 275.It net.inet.udp.checksum Ta integer Ta yes 276.It net.inet.udp.baddynamic Ta array Ta yes 277.It net.inet.udp.recvspace Ta integer Ta yes 278.It net.inet.udp.sendspace Ta integer Ta yes 279.It net.inet.gre.allow Ta integer Ta yes 280.It net.inet.gre.wccp Ta integer Ta yes 281.It net.inet.esp.enable Ta integer Ta yes 282.It net.inet.esp.udpencap Ta integer Ta yes 283.It net.inet.esp.udpencap_port Ta integer Ta yes 284.It net.inet.ah.enable Ta integer Ta yes 285.It net.inet.mobileip.allow Ta integer Ta yes 286.It net.inet.etherip.allow Ta integer Ta yes 287.It net.inet.ipcomp.enable Ta integer Ta yes 288.It net.inet.carp.allow Ta integer Ta yes 289.It net.inet.carp.preempt Ta integer Ta yes 290.It net.inet.carp.log Ta integer Ta yes 291.It net.inet6.ip6.forwarding Ta integer Ta yes 292.It net.inet6.ip6.redirect Ta integer Ta yes 293.It net.inet6.ip6.hlim Ta integer Ta yes 294.It net.inet6.ip6.maxfragpackets Ta integer Ta yes 295.It net.inet6.ip6.log_interval Ta integer Ta yes 296.It net.inet6.ip6.hdrnestlimit Ta integer Ta yes 297.It net.inet6.ip6.dad_count Ta integer Ta yes 298.It net.inet6.ip6.auto_flowlabel Ta integer Ta yes 299.It net.inet6.ip6.defmcasthlim Ta integer Ta yes 300.It net.inet6.ip6.use_deprecated Ta integer Ta yes 301.It net.inet6.ip6.rr_prune Ta integer Ta yes 302.It net.inet6.ip6.v6only Ta integer Ta no 303.It net.inet6.ip6.maxfrags Ta integer Ta yes 304.It net.inet6.ip6.mforwarding Ta integer Ta yes 305.It net.inet6.ip6.multipath Ta integer Ta yes 306.It net.inet6.ip6.multicast_mtudisc Ta integer Ta yes 307.It net.inet6.ip6.neighborgcthresh Ta integer Ta yes 308.It net.inet6.ip6.maxifprefixes Ta integer Ta yes 309.It net.inet6.ip6.maxifdefrouters Ta integer Ta yes 310.It net.inet6.ip6.maxdynroutes Ta integer Ta yes 311.It net.inet6.ip6.dad_pending Ta integer Ta yes 312.It net.inet6.ip6.mtudisctimeout Ta integer Ta yes 313.It net.inet6.icmp6.rediraccept Ta integer Ta yes 314.It net.inet6.icmp6.redirtimeout Ta integer Ta yes 315.It net.inet6.icmp6.nd6_prune Ta integer Ta yes 316.It net.inet6.icmp6.nd6_delay Ta integer Ta yes 317.It net.inet6.icmp6.nd6_umaxtries Ta integer Ta yes 318.It net.inet6.icmp6.nd6_mmaxtries Ta integer Ta yes 319.It net.inet6.icmp6.errppslimit Ta integer Ta yes 320.It net.inet6.icmp6.nd6_maxnudhint Ta integer Ta yes 321.It net.inet6.icmp6.mtudisc_hiwat Ta integer Ta yes 322.It net.inet6.icmp6.mtudisc_lowat Ta integer Ta yes 323.It net.inet6.icmp6.nd6_debug Ta integer Ta yes 324.It net.mpls.ttl Ta integer Ta yes 325.It net.mpls.ifq.len Ta integer Ta no 326.It net.mpls.ifq.maxlen Ta integer Ta yes 327.It net.mpls.ifq.drops Ta integer Ta no 328.It net.mpls.maxloop_inkernel Ta integer Ta yes 329.It net.mpls.mapttl_ip Ta integer Ta yes 330.It net.mpls.mapttl_ip6 Ta integer Ta yes 331.It net.pipex.enable Ta integer Ta yes 332.It net.pipex.inq.len Ta integer Ta no 333.It net.pipex.inq.maxlen Ta integer Ta yes 334.It net.pipex.inq.drops Ta integer Ta no 335.It net.pipex.outq.len Ta integer Ta no 336.It net.pipex.outq.maxlen Ta integer Ta yes 337.It net.pipex.outq.drops=0 Ta integer Ta no 338.It debug.syncprt Ta integer Ta yes 339.It debug.busyprt Ta integer Ta yes 340.It debug.doclusterread Ta integer Ta yes 341.It debug.doclusterwrite Ta integer Ta yes 342.It debug.doreallocblks Ta integer Ta yes 343.It debug.doasyncfree Ta integer Ta yes 344.It debug.prtrealloc Ta integer Ta yes 345.It hw.machine Ta string Ta no 346.It hw.model Ta string Ta no 347.It hw.ncpu Ta integer Ta no 348.It hw.byteorder Ta integer Ta no 349.It hw.physmem Ta int64_t Ta no 350.It hw.usermem Ta int64_t Ta no 351.It hw.pagesize Ta integer Ta no 352.It hw.diskstats Ta struct Ta no 353.It hw.disknames Ta string Ta no 354.It hw.diskcount Ta integer Ta no 355.It hw.sensors.<xname>.<type><numt> Ta struct Ta no 356.It hw.cpuspeed Ta integer Ta no 357.It hw.setperf Ta integer Ta yes 358.It hw.vendor Ta string Ta no 359.It hw.product Ta string Ta no 360.It hw.version Ta string Ta no 361.It hw.serialno Ta string Ta no 362.It hw.uuid Ta string Ta no 363.It hw.ncpufound Ta integer Ta no 364.It hw.allowpowerdown Ta integer Ta yes 365.It machdep.console_device Ta dev_t Ta no 366.It machdep.unaligned_print Ta integer Ta yes 367.It machdep.unaligned_fix Ta integer Ta yes 368.It machdep.unaligned_sigbus Ta integer Ta yes 369.It machdep.apmwarn Ta integer Ta yes 370.It machdep.apmhalt Ta integer Ta yes 371.It machdep.kbdreset Ta integer Ta yes 372.It machdep.userldt Ta integer Ta yes 373.It machdep.osfxsr Ta integer Ta no 374.It machdep.sse Ta integer Ta no 375.It machdep.sse2 Ta integer Ta no 376.It machdep.xcrypt Ta integer Ta no 377.It machdep.allowaperture Ta integer Ta yes 378.It machdep.led_blink Ta integer Ta yes 379.It machdep.ceccerrs Ta integer Ta no 380.It machdep.cecclast Ta quad Ta no 381.It ddb.radix Ta integer Ta yes 382.It ddb.max_width Ta integer Ta yes 383.It ddb.max_line Ta integer Ta yes 384.It ddb.tab_stop_width Ta integer Ta yes 385.It ddb.panic Ta integer Ta yes 386.It ddb.console Ta integer Ta yes 387.It ddb.log Ta integer Ta yes 388.It ddb.trigger Ta integer Ta yes 389.It vfs.mounts.* Ta struct Ta no 390.It vfs.ffs.doclusterread Ta integer Ta yes 391.It vfs.ffs.doclusterwrite Ta integer Ta yes 392.It vfs.ffs.doreallocblks Ta integer Ta yes 393.It vfs.ffs.doasyncfree Ta integer Ta yes 394.It vfs.ffs.max_softdeps Ta integer Ta yes 395.It vfs.ffs.sd_tickdelay Ta integer Ta yes 396.It vfs.ffs.sd_worklist_push Ta integer Ta no 397.It vfs.ffs.sd_blk_limit_push Ta integer Ta no 398.It vfs.ffs.sd_ino_limit_push Ta integer Ta no 399.It vfs.ffs.sd_blk_limit_hit Ta integer Ta no 400.It vfs.ffs.sd_ino_limit_hit Ta integer Ta no 401.It vfs.ffs.sd_sync_limit_hit Ta integer Ta no 402.It vfs.ffs.sd_indir_blk_ptrs Ta integer Ta no 403.It vfs.ffs.sd_inode_bitmap Ta integer Ta no 404.It vfs.ffs.sd_direct_blk_ptrs Ta integer Ta no 405.It vfs.ffs.sd_dir_entry Ta integer Ta no 406.It vfs.ffs.dirhash_dirsize Ta integer Ta yes 407.It vfs.ffs.dirhash_maxmem Ta integer Ta yes 408.It vfs.ffs.dirhash_mem Ta integer Ta no 409.It vfs.nfs.iothreads Ta integer Ta yes 410.It vfs.fuse.fusefs_open_devices Ta integer Ta no 411.It vfs.fuse.fusefs_fbufs_in Ta integer Ta no 412.It vfs.fuse.fusefs_fbufs_wait Ta integer Ta no 413.It vfs.fuse.fusefs_pool_pages Ta integer Ta no 414.El 415.Pp 416The 417.Nm 418program can extract information about the filesystems that have been compiled 419into the running system. 420This information can be obtained by using the command: 421.Pp 422.Dl $ sysctl vfs.mounts 423.Pp 424By default, only filesystems that are actively being used are listed. 425Use of the 426.Fl A 427flag lists all the filesystems compiled into the running kernel. 428.Sh FILES 429.Bl -tag -width <uvm/uvm_swap_encrypt.h> -compact 430.It Aq Pa sys/sysctl.h 431definitions for top level identifiers and second level kernel and hardware 432identifiers 433.It Aq Pa dev/rndvar.h 434definitions for 435.Xr random 4 436device's statistics structure 437.It Aq Pa sys/socket.h 438definitions for second level network identifiers 439.It Aq Pa sys/gmon.h 440definitions for third level profiling identifiers 441.It Aq Pa uvm/uvm_param.h 442definitions for second level virtual memory identifiers 443.It Aq Pa uvm/uvm_swap_encrypt.h 444definitions for third level virtual memory identifiers 445.It Aq Pa netinet/in.h 446definitions for third level IPv4/v6 identifiers and 447fourth level IPv4/v6 identifiers 448.It Aq Pa netinet/ip_divert.h 449definitions for fourth level divert identifiers 450.It Aq Pa netinet/icmp_var.h 451definitions for fourth level ICMP identifiers 452.It Aq Pa netinet6/icmp6.h 453definitions for fourth level ICMPv6 identifiers 454.It Aq Pa netinet/tcp_var.h 455definitions for fourth level TCP identifiers 456.It Aq Pa netinet/udp_var.h 457definitions for fourth level UDP identifiers 458.It Aq Pa ddb/db_var.h 459definitions for second level ddb identifiers 460.It Aq Pa sys/mount.h 461definitions for second level vfs identifiers 462.It Aq Pa nfs/nfs.h 463definitions for third level NFS identifiers 464.It Aq Pa miscfs/fuse/fusefs.h 465definitions for third level fusefs identifiers 466.It Aq Pa ufs/ffs/ffs_extern.h 467definitions for third level FFS identifiers 468.It Aq Pa machine/cpu.h 469definitions for second level CPU identifiers 470.El 471.Sh EXAMPLES 472To retrieve the maximum number of processes allowed 473in the system: 474.Pp 475.Dl $ sysctl kern.maxproc 476.Pp 477To set the maximum number of processes allowed 478in the system to 1000: 479.Pp 480.Dl # sysctl kern.maxproc=1000 481.Pp 482To retrieve information about the system clock rate: 483.Pp 484.Dl $ sysctl kern.clockrate 485.Pp 486To retrieve information about the load average history: 487.Pp 488.Dl $ sysctl vm.loadavg 489.Pp 490To make the 491.Xr chown 2 492system call use traditional 493.Bx 494semantics (don't clear setuid/setgid bits): 495.Pp 496.Dl # sysctl fs.posix.setuid=0 497.Pp 498To set the list of reserved TCP ports that should not be allocated 499by the kernel dynamically: 500.Pp 501.Dl # sysctl net.inet.tcp.baddynamic=749,750,751,760,761,871 502.Dl # sysctl net.inet.udp.baddynamic=749,750,751,760,761,871,1024-2048 503.Pp 504This can be used to keep daemons 505from stealing a specific port that another program needs to function. 506List elements may be separated by commas and/or whitespace; 507a hyphen may be used to specify a range of ports. 508.Pp 509It is also possible to add or remove ports from the current list: 510.Bd -literal -offset indent 511# sysctl net.inet.tcp.baddynamic=+748,6000-6999 512# sysctl net.inet.tcp.baddynamic=-871 513.Ed 514.Pp 515To set the amount of shared memory available in the system and 516the maximum number of shared memory segments: 517.Bd -literal -offset indent 518# sysctl kern.shminfo.shmmax=33554432 519# sysctl kern.shminfo.shmseg=32 520.Ed 521.Pp 522To place core dumps from 523.Xr issetugid 2 524programs (in this example 525.Xr bgpd 8 ) 526into a safe place for debugging purposes: 527.Bd -literal -offset indent 528# mkdir /var/crash/bgpd 529# chmod 700 /var/crash/bgpd 530# sysctl kern.nosuidcoredump=3 531.Ed 532.Sh SEE ALSO 533.Xr sysctl 3 , 534.Xr options 4 , 535.Xr sysctl.conf 5 536.Sh HISTORY 537.Nm 538first appeared in 539.Bx 4.4 . 540