SYSCTL(8)               NetBSD System Manager's Manual               SYSCTL(8)

NAME
     sysctl - get or set kernel state

SYNOPSIS
     sysctl [-n] name ...
     sysctl [-n] [-q] -w name=value ...
     sysctl [-n] -a
     sysctl [-n] -A
     sysctl [-n] [-q] -f file

DESCRIPTION
     The sysctl utility retrieves kernel state and allows processes with ap-
     propriate 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 -a flag can be used
     to list all the currently available string or integer values.  The -A
     flag will list all the known MIB names including tables.  Those with
     string or integer values will be printed as with the -a flag; for the
     table values, the name of the utility to retrieve them is given.

     The -n flag specifies that the printing of the field name should be sup-
     pressed and that only its value should be output.  This flag is useful
     for setting shell variables.  For example, to save the pagesize in vari-
     able psize, use:
           set psize=`sysctl -n hw.pagesize`

     If just a MIB style name is given, the corresponding value is retrieved.
     If a value is to be set, the -w flag must be specified and the MIB name
     followed by an equal sign and the new value to be used.

     The -f flag specifies the name of a file to read and process.  Blank
     lines and comments (beginning with `#') are ignored.  Line continuations
     with `\' are permitted.  Remaining lines are processed similarly to com-
     mand line arguments of the form name or name=value.  The -w flag is im-
     plied by -f.

     The -q flag may be used with -f and -w to indicate that nothing should be
     printed for writes unless an error is detected.

     The `proc' top-level MIB has a special semantic: it represent per-process
     values and as such may differ from one process to another. The second-
     level name is the pid of the process (in decimal form), or the special
     word `curproc'.  For variables below `proc.<pid>.rlimit', the integer
     value may be replaced with the string `unlimited' if it matches the magic
     value used to disable a limit.

     The information available from sysctl consists of integers, strings, and
     tables.  The tabular information can only be retrieved by special purpose
     programs such as ps, systat, and netstat.  The string and integer infor-
     mation is summarized below.  For a detailed description of these variable
     see sysctl(3).  The changeable column indicates whether a process with
     appropriate privilege can change the value.

     Name                                         Type          Changeable
     ddb.fromconsole                              integer       yes
     ddb.lines                                    integer       yes
     ddb.maxoff                                   integer       yes
     ddb.maxwidth                                 integer       yes
     ddb.onpanic                                  integer       yes
     ddb.radix                                    integer       yes
     ddb.tabstops                                 integer       yes
     hw.alignbytes                                integer       no
     hw.byteorder                                 integer       no
     hw.disknames                                 string        no
     hw.diskstats                                 struct        no
     hw.machine                                   string        no
     hw.machine_arch                              string        no
     hw.model                                     string        no
     hw.ncpu                                      integer       no
     hw.pagesize                                  integer       no
     hw.physmem                                   integer       no
     hw.usermem                                   integer       no
     hw.cnmagic                                   string        yes
     kern.argmax                                  integer       no
     kern.autonicetime                            integer       yes
     kern.autoniceval                             integer       yes
     kern.boottime                                struct        no
     kern.chown_restricted                        integer       no
     kern.clockrate                               struct        no
     kern.defcorename                             string        yes
     kern.fsync                                   integer       no
     kern.hostid                                  integer       yes
     kern.hostname                                string        yes
     kern.iov_max                                 integer       no
     kern.job_control                             integer       no
     kern.link_max                                integer       no
     kern.login_name_max                          integer       no
     kern.logsigexit                              integer       yes
     kern.max_canon                               integer       no
     kern.max_input                               integer       no
     kern.maxfiles                                integer       yes
     kern.maxpartitions                           integer       no
     kern.maxproc                                 integer       yes
     kern.maxptys                                 integer       yes, special
     kern.maxvnodes                               integer       raise only
     kern.mapped_files                            integer       no
     kern.memlock                                 integer       no
     kern.memlock_rage                            integer       no
     kern.memory_protection                       integer       no
     kern.mbuf.mblowat                            integer       yes
     kern.mbuf.mcllowat                           integer       yes
     kern.mbuf.mclsize                            integer       no
     kern.mbuf.msize                              integer       no
     kern.mbuf.nmbclusters                        integer       raise only
     kern.msgbufsize                              integer       no
     kern.name_max                                integer       no
     kern.ngroups                                 integer       no
     kern.no_trunc                                integer       no
     kern.osrelease                               string        no
     kern.osrevision                              integer       no
     kern.ostype                                  string        no
     kern.path_max                                integer       no
     kern.pipe.maxkvasz                           integer       yes
     kern.pipe.maxloankvasz                       integer       yes
     kern.pipe.maxbigpipes                        integer       yes
     kern.pipe.nbigpipes                          integer       no
     kern.pipe.kvasize                            integer       no
     kern.posix1version                           integer       no
     kern.rawpartition                            integer       no
     kern.saved_ids                               integer       no
     kern.securelevel                             integer       raise only
     kern.synchronized_io                         integer       no
     kern.sysvmsg                                 integer       no
     kern.sysvsem                                 integer       no
     kern.sysvshm                                 integer       no
     kern.tkstat.nin                              quad          no
     kern.tkstat.nout                             quad          no
     kern.tkstat.cancc                            quad          no
     kern.tkstat.rawcc                            quad          no
     kern.vdisable                                integer       no
     kern.version                                 string        no
     machdep.console_device                       dev_t         no
     net.inet.icmp.maskrepl                       integer       yes
     net.inet.icmp.errppslimit                    integer       yes
     net.inet.icmp.rediraccept                    integer       yes
     net.inet.icmp.redirtimeout                   integer       yes
     net.inet.ip.allowsrcrt                       integer       yes
     net.inet.ip.anonportmax                      integer       yes
     net.inet.ip.anonportmin                      integer       yes
     net.inet.ip.directed-broadcast               integer       yes
     net.inet.ip.forwarding                       integer       yes
     net.inet.ip.forwsrcrt                        integer       yes
     net.inet.ip.maxfragpacket                    integer       yes
     net.inet.ip.lowportmax                       integer       yes
     net.inet.ip.lowportmin                       integer       yes
     net.inet.ip.mtudisc                          integer       yes
     net.inet.ip.mtudisctimeout                   integer       yes
     net.inet.ip.redirect                         integer       yes
     net.inet.ip.subnetsarelocal                  integer       yes
     net.inet.ip.ttl                              integer       yes
     net.inet.ipsec.ah_cleartos                   integer       yes
     net.inet.ipsec.ah_net_deflev                 integer       yes
     net.inet.ipsec.ah_offsetmask                 integer       yes
     net.inet.ipsec.ah_trans_deflev               integer       yes
     net.inet.ipsec.def_policy                    integer       yes
     net.inet.ipsec.dfbit                         integer       yes
     net.inet.ipsec.ecn                           integer       yes
     net.inet.ipsec.esp_net_deflev                integer       yes
     net.inet.ipsec.esp_trans_deflev              integer       yes
     net.inet.ipsec.inbound_call_ike              integer       yes
     net.inet.tcp.ack_on_push                     integer       yes
     net.inet.tcp.compat_42                       integer       yes
     net.inet.tcp.cwm                             integer       yes
     net.inet.tcp.cwm_burstsize                   integer       yes
     net.inet.tcp.init_win                        integer       yes
     net.inet.tcp.keepcnt                         integer       yes
     net.inet.tcp.keepidle                        integer       yes
     net.inet.tcp.keepintvl                       integer       yes
     net.inet.tcp.log_refused                     integer       yes
     net.inet.tcp.mss_ifmtu                       integer       yes
     net.inet.tcp.mssdflt                         integer       yes
     net.inet.tcp.recvspace                       integer       yes
     net.inet.tcp.rfc1323                         integer       yes
     net.inet.tcp.rstppslimit                     integer       yes
     net.inet.tcp.sack                            integer       yes
     net.inet.tcp.sendspace                       integer       yes
     net.inet.tcp.slowhz                          integer       no
     net.inet.tcp.syn_bucket_limit                integer       yes
     net.inet.tcp.syn_cache_interval              integer       yes
     net.inet.tcp.syn_cache_limit                 integer       yes
     net.inet.tcp.timestamps                      integer       yes
     net.inet.tcp.win_scale                       integer       yes
     net.inet.udp.checksum                        integer       yes
     net.inet.udp.recvspace                       integer       yes
     net.inet.udp.sendspace                       integer       yes
     net.inet6.icmp6.errppslimit                  integer       yes
     net.inet6.icmp6.mtudisc_hiwat                integer       yes
     net.inet6.icmp6.mtudisc_lowat                integer       yes
     net.inet6.icmp6.nd6_debug                    integer       yes
     net.inet6.icmp6.nd6_delay                    integer       yes
     net.inet6.icmp6.nd6_maxnudhint               integer       yes
     net.inet6.icmp6.nd6_mmaxtries                integer       yes
     net.inet6.icmp6.nd6_prune                    integer       yes
     net.inet6.icmp6.nd6_umaxtries                integer       yes
     net.inet6.icmp6.nd6_useloopback              integer       yes
     net.inet6.icmp6.nodeinfo                     integer       yes
     net.inet6.icmp6.rediraccept                  integer       yes
     net.inet6.icmp6.redirtimeout                 integer       yes
     net.inet6.ip6.accept_rtadv                   integer       yes
     net.inet6.ip6.anonportmax                    integer       yes
     net.inet6.ip6.anonportmin                    integer       yes
     net.inet6.ip6.auto_flowlabel                 integer       yes
     net.inet6.ip6.v6only                         integer       yes
     net.inet6.ip6.dad_count                      integer       yes
     net.inet6.ip6.defmcasthlim                   integer       yes
     net.inet6.ip6.forwarding                     integer       yes
     net.inet6.ip6.gif_hlim                       integer       yes
     net.inet6.ip6.hdrnestlimit                   integer       yes
     net.inet6.ip6.hlim                           integer       yes
     net.inet6.ip6.kame_version                   string        no
     net.inet6.ip6.keepfaith                      integer       yes
     net.inet6.ip6.log_interval                   integer       yes
     net.inet6.ip6.lowportmax                     integer       yes
     net.inet6.ip6.lowportmin                     integer       yes
     net.inet6.ip6.maxfragpackets                 integer       yes
     net.inet6.ip6.redirect                       integer       yes
     net.inet6.ip6.rr_prune                       integer       yes
     net.inet6.ip6.use_deprecated                 integer       yes
     net.inet6.ipsec6.ah_net_deflev               integer       yes
     net.inet6.ipsec6.ah_trans_deflev             integer       yes
     net.inet6.ipsec6.def_policy                  integer       yes
     net.inet6.ipsec6.ecn                         integer       yes
     net.inet6.ipsec6.esp_net_deflev              integer       yes
     net.inet6.ipsec6.esp_trans_deflev            integer       yes
     net.inet6.ipsec6.inbound_call_ike            integer       yes
     net.inet6.udp6.recvspace                     integer       yes
     net.inet6.udp6.sendspace                     integer       yes
     net.key.acq_exp_int                          integer       yes
     net.key.acq_maxtime                          integer       yes
     net.key.ah_keymin                            integer       yes
     net.key.debug                                integer       yes
     net.key.esp_auth                             integer       yes
     net.key.esp_keymin                           integer       yes
     net.key.kill_int                             integer       yes
     net.key.random_int                           integer       yes
     net.key.spi_max_value                        integer       yes
     net.key.spi_min_value                        integer       yes
     net.key.spi_try                              integer       yes
     proc.<pid>.corename                          string        yes
     proc.<pid>.rlimit.coredumpsize.hard          integer       yes
     proc.<pid>.rlimit.coredumpsize.soft          integer       yes
     proc.<pid>.rlimit.cputime.hard               integer       yes
     proc.<pid>.rlimit.cputime.soft               integer       yes
     proc.<pid>.rlimit.datasize.hard              integer       yes
     proc.<pid>.rlimit.datasize.soft              integer       yes
     proc.<pid>.rlimit.filesize.hard              integer       yes
     proc.<pid>.rlimit.filesize.soft              integer       yes
     proc.<pid>.rlimit.maxproc.hard               integer       yes
     proc.<pid>.rlimit.maxproc.soft               integer       yes
     proc.<pid>.rlimit.memorylocked.hard          integer       yes
     proc.<pid>.rlimit.memorylocked.soft          integer       yes
     proc.<pid>.rlimit.memoryuse.hard             integer       yes
     proc.<pid>.rlimit.memoryuse.soft             integer       yes
     proc.<pid>.rlimit.stacksize.hard             integer       yes
     proc.<pid>.rlimit.stacksize.soft             integer       yes
     user.bc_base_max                             integer       no
     user.bc_dim_max                              integer       no
     user.bc_scale_max                            integer       no
     user.bc_string_max                           integer       no
     user.coll_weights_max                        integer       no
     user.cs_path                                 string        no
     user.expr_nest_max                           integer       no
     user.line_max                                integer       no
     user.posix2_c_bind                           integer       no
     user.posix2_c_dev                            integer       no
     user.posix2_char_term                        integer       no
     user.posix2_fort_dev                         integer       no
     user.posix2_fort_run                         integer       no
     user.posix2_localedef                        integer       no
     user.posix2_sw_dev                           integer       no
     user.posix2_upe                              integer       no
     user.posix2_version                          integer       no
     user.re_dup_max                              integer       no
     vendor.<vendor>.*                            ?             vendor
                                                                specific
     vfs.generic.usermount                        integer       yes
     vfs.nfs.iothreads                            integer       yes
     vm.anonmax                                   integer       yes
     vm.anonmin                                   integer       yes
     vm.execmax                                   integer       yes
     vm.execmin                                   integer       yes
     vm.filemax                                   integer       yes
     vm.filemin                                   integer       yes
     vm.loadavg                                   struct        no
     vm.nkmempages                                integer       no
     vm.uvmexp                                    struct        no
     vm.uvmexp2                                   struct        no
     vm.vmmeter                                   struct        no

     Entries found under ``vendor.<vendor>'' are left to be specified (and
     used) by vendors using the NetBSD operating system in their products.
     Values and structure are vendor-defined, and no registry exists right
     now.

FILES
     <sys/sysctl.h>         definitions for top level identifiers, second lev-
                            el kernel and hardware identifiers, and user level
                            identifiers
     <sys/socket.h>         definitions for second level network identifiers
     <sys/gmon.h>           definitions for third level profiling identifiers
     <uvm/uvm_param.h>      definitions for second level virtual memory iden-
                            tifiers
     <netinet/in.h>         definitions for third level IPv4/v6 identifiers
                            and fourth level IPv4/v6 identifiers
     <netinet/icmp_var.h>   definitions for fourth level ICMP identifiers
     <netinet/icmp6.h>      definitions for fourth level ICMPv6 identifiers
     <netinet/tcp_var.h>    definitions for fourth level TCP identifiers
     <netinet/udp_var.h>    definitions for fourth level UDP identifiers
     <netinet6/udp6_var.h>  definitions for fourth level IPv6 UDP identifiers
     <netinet6/ipsec.h>     definitions for fourth level IPsec identifiers
     <netkey/key_var.h>     definitions for third level PF_KEY identifiers

EXAMPLES
     For example, to retrieve the maximum number of processes allowed in the
     system, one would use the following request:
           sysctl kern.maxproc

     To set the maximum number of processes allowed in the system to 1000, one
     would use the following request:
           sysctl -w kern.maxproc=1000

     Information about the system clock rate may be obtained with:
           sysctl kern.clockrate

     Information about the load average history may be obtained with:
           sysctl vm.loadavg

     To view the values of the per-process variables of the current shell, the
     request:
           sysctl proc.$$
     can be used if the shell interpreter replaces $$ with it's pid (this is
     true for most shells).

     To redirect core dumps to the /var/tmp/<username> directory,
           sysctl -w proc.$$.corename=/var/tmp/%u/%n.core
     Shall be used.
           sysctl -w proc.curproc.corename=/var/tmp/%u/%n.core
     changes the value for the sysctl process itself, and will not have the
     desired effect.

SEE ALSO
     sysctl(3)

HISTORY
     sysctl first appeared in 4.4BSD.

NetBSD 1.6                       June 6, 1993                                6

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©1994 Man-cgi 1.15, Panagiotis Christias
©1996-2017 Modified for NetBSD by Kimmo Suominen