SYSCTL(8) NetBSD System Manager's Manual SYSCTL(8)
NAME
sysctl - get or set kernel state
SYNOPSIS
sysctl [-n] name ... sysctl [-n] -w name=value ... sysctl [-n] -aA
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 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 summaried 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 kern.ostype string no kern.osrelease string no kern.osrevision integer no kern.version string no kern.maxvnodes integer yes kern.maxproc integer yes kern.maxfiles integer yes kern.maxpartitions integer no kern.rawpartition integer no kern.msgbufsize integer no kern.argmax integer no kern.securelevel integer raise only kern.hostname string yes kern.hostid integer yes kern.clockrate struct no kern.posix1version integer no kern.ngroups integer no kern.job_control integer no kern.saved_ids integer no kern.link_max integer no kern.max_canon integer no kern.max_input integer no kern.name_max integer no kern.path_max integer no kern.pipe_buf integer no kern.chown_restricted integer no kern.no_trunc integer no kern.vdisable integer no kern.boottime struct no kern.autonicetime integer yes kern.autoniceval integer yes kern.fsync integer no kern.sysvmsg integer no kern.sysvsem integer no kern.sysvshm integer no kern.shortcorename integer yes kern.synchronized_io integer no kern.iov_max integer no vm.loadavg struct no machdep.console_device dev_t no net.inet.ip.forwarding integer yes net.inet.ip.redirect integer yes net.inet.ip.ttl integer yes net.inet.ip.forwsrcrt integer yes net.inet.ip.directed-broadcast integer yes net.inet.ip.allowsrcrt integer yes net.inet.ip.subnetsarelocal integer yes net.inet.ip.mtudisc integer yes net.inet.ip.anonportmin integer yes net.inet.ip.anonportmax integer yes net.inet.ip.mtudisctimeout integer yes net.inet.icmp.maskrepl integer yes net.inet.tcp.rfc1323 integer yes net.inet.tcp.sendspace integer yes net.inet.tcp.recvspace integer yes net.inet.tcp.mssdflt integer yes net.inet.tcp.syn_cache_limit integer yes net.inet.tcp.syn_bucket_limit integer yes net.inet.tcp.syn_cache_interval integer yes net.inet.tcp.init_win integer yes net.inet.tcp.init_win integer yes net.inet.tcp.mss_ifmtu integer yes net.inet.tcp.sack integer yes net.inet.tcp.win_scale integer yes net.inet.tcp.timestamps 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.ack_on_push integer yes net.inet.tcp.keepidle integer yes net.inet.tcp.keepintvl integer yes net.inet.tcp.keepcnt integer yes net.inet.tcp.slowhz integer no net.inet.udp.checksum integer yes net.inet.udp.sendspace integer yes net.inet.udp.recvspace integer yes hw.machine string no hw.model string no hw.ncpu integer no hw.byteorder integer no hw.physmem integer no hw.usermem integer no hw.pagesize integer no hw.machine_arch string no user.cs_path string no 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.expr_nest_max integer no user.line_max integer no user.re_dup_max integer no user.posix2_version 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 ddb.radix integer yes ddb.maxoff integer yes ddb.maxwidth integer yes ddb.tabstops integer yes ddb.lines integer yes ddb.onpanic integer yes
EXAMPLES
For example, to retrieve the maximum number of processes allowed in the system, one would use the follow request: sysctl kern.maxproc To set the maximum number of processes allowed in the system to 1000, one would use the follow 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
FILES
<sys/sysctl.h> definitions for top level identifiers, second level 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 <vm/vm_param.h> definitions for second level virtual memory identi- fiers <netinet/in.h> definitions for third level Internet identifiers and fourth level IP identifiers <netinet/icmp_var.h> definitions for fourth level ICMP identifiers <netinet/udp_var.h> definitions for fourth level UDP identifiers
SEE ALSO
sysctl(3)
HISTORY
sysctl first appeared in 4.4BSD. NetBSD 1.4 June 6, 1993 3
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