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

NAME

     sysctl -- get or set kernel state

SYNOPSIS

     sysctl [-bdehiNnoqx] name[=value] ...
     sysctl [-bdehNnoqx] -a

DESCRIPTION

     The 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 following options are available:

     -A      Equivalent to -o -a (for compatibility).

     -a      List all the currently available non-opaque values.  This option is ignored if one or more variable names are specified on the com-
	     mand line.

     -b      Force the value of the variable(s) to be output in raw, binary format.  No names are printed and no terminating newlines are output.
	     This is mostly useful with a single variable.

     -d      Print the description of the variable instead of its value.

     -e      Separate the name and the value of the variable(s) with '='.  This is useful for producing output which can be fed back to the sysctl
	     utility.  This option is ignored if either -N or -n is specified, or a variable is being set.

     -h      Format output for human, rather than machine, readability.

     -i      Ignore unknown OIDs.  The purpose is to make use of sysctl for collecting data from a variety of machines (not all of which are nec-
	     essarily running exactly the same software) easier.

     -N      Show only variable names, not their values.  This is particularly useful with shells that offer programmable completion.  To enable
	     completion of variable names in zsh(1) (ports/shells/zsh), use the following code:

		   listsysctls () { set -A reply $(sysctl -AN ${1%.*}) }
		   compctl -K listsysctls sysctl

	     To enable completion of variable names in tcsh(1), use:

		   complete sysctl 'n/*/`sysctl -Na`/'

     -n      Show only variable values, not their names.  This option is useful for setting shell variables.  For instance, to save the pagesize
	     in variable psize, use:

		   set psize=`sysctl -n hw.pagesize`

     -o      Show opaque variables (which are normally suppressed).  The format and length are printed, as well as a hex dump of the first sixteen
	     bytes of the value.

     -q      Suppress some warnings generated by sysctl to standard error.

     -X      Equivalent to -x -a (for compatibility).

     -x      As -o, but prints a hex dump of the entire value instead of just the first few bytes.

     The information available from sysctl consists of integers, strings, and opaque types.  The sysctl utility only knows about a couple of
     opaque types, and will resort to hexdumps for the rest.  The opaque information is much more useful if retrieved by special purpose programs
     such as ps(1), systat(1), and netstat(1).

     The string and integer information 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.  String and integer values can be set
     using sysctl.

     Name					 Type	       Changeable
     hw.activecpu				 integer       no
     hw.busfrequency				 integer       no
     hw.busfrequency_max			 integer       no
     hw.busfrequency_min			 integer       no
     hw.byteorder				 integer       no
     hw.cacheconfig				 struct        no
     hw.cachelinesize				 integer       no
     hw.cachesize				 struct        no
     hw.cpu64bit_capable			 integer       no
     hw.cpufamily				 integer       no
     hw.cpufrequency				 integer       no
     hw.cpufrequency_max			 integer       no
     hw.cpufrequency_min			 integer       no
     hw.cpusubtype				 integer       no
     hw.cputhreadtype				 integer       no
     hw.cputype 				 integer       no
     hw.l1dcachesize				 integer       no
     hw.l1icachesize				 integer       no
     hw.l2cachesize				 integer       no
     hw.l3cachesize				 integer       no
     hw.logicalcpu				 integer       no
     hw.logicalcpu_max				 integer       no
     hw.memsize 				 integer       no
     hw.ncpu					 integer       no
     hw.packages				 integer       no
     hw.pagesize				 integer       no
     hw.physicalcpu				 integer       no
     hw.physicalcpu_max 			 integer       no
     hw.tbfrequency				 integer       no
     kern.argmax				 integer       no
     kern.bootargs				 string        no
     kern.boottime				 struct        no
     kern.clockrate				 struct        no
     kern.coredump				 integer       yes
     kern.corefile				 string        yes
     kern.flush_cache_on_write			 integer       yes
     kern.hostid				 integer       yes
     kern.hostname				 string        yes
     kern.job_control				 integer       no
     kern.maxfiles				 integer       yes
     kern.maxfilesperproc			 integer       yes
     kern.maxnbuf				 integer       yes
     kern.maxproc				 integer       yes
     kern.maxprocperuid 			 integer       yes
     kern.maxvnodes				 integer       yes
     kern.msgbuf				 integer       yes
     kern.nbuf					 integer       no
     kern.netboot				 integer       no
     kern.ngroups				 integer       no
     kern.nisdomainname 			 string        yes
     kern.num_files				 integer       no
     kern.num_tasks				 integer       no
     kern.num_taskthreads			 integer       no
     kern.num_threads				 integer       no
     kern.num_vnodes				 integer       no
     kern.nx					 integer       yes
     kern.osrelease				 string        no
     kern.osrevision				 integer       no
     kern.ostype				 string        no
     kern.osversion				 string        yes
     kern.posix1version 			 integer       no
     kern.procname				 string        yes
     kern.safeboot				 integer       no
     kern.saved_ids				 integer       no
     kern.secure_kernel 			 integer       no
     kern.securelevel				 integer       yes
     kern.singleuser				 integer       no
     kern.sleeptime				 struct        no
     kern.slide 				 integer       no
     kern.stack_depth_max			 integer       no
     kern.stack_size				 integer       no
     kern.sugid_coredump			 integer       yes
     kern.sugid_scripts 			 integer       yes
     kern.symfile				 string        no
     kern.usrstack				 integer       no
     kern.usrstack64				 integer       no
     kern.uuid					 string        no
     kern.version				 string        no
     kern.waketime				 struct        no
     machdep.cpu.address_bits.physical		 integer       no
     machdep.cpu.address_bits.virtual		 integer       no
     machdep.cpu.brand				 integer       no
     machdep.cpu.brand_string			 string        no
     machdep.cpu.cache.L2_associativity 	 integer       no
     machdep.cpu.cache.linesize 		 integer       no
     machdep.cpu.cache.size			 integer       no
     machdep.cpu.core_count			 integer       no
     machdep.cpu.cores_per_package		 integer       no
     machdep.cpu.extfamily			 integer       no
     machdep.cpu.extfeature_bits		 integer       no
     machdep.cpu.extfeatures			 string        no
     machdep.cpu.extmodel			 integer       no
     machdep.cpu.family 			 integer       no
     machdep.cpu.feature_bits			 integer       no
     machdep.cpu.features			 string        no
     machdep.cpu.leaf7_feature_bits		 integer       no
     machdep.cpu.leaf7_features 		 string        no
     machdep.cpu.logical_per_package		 integer       no
     machdep.cpu.max_basic			 integer       no
     machdep.cpu.max_ext			 integer       no
     machdep.cpu.microcode_version		 integer       no
     machdep.cpu.model				 integer       no
     machdep.cpu.processor_flag 		 integer       no
     machdep.cpu.signature			 integer       no
     machdep.cpu.stepping			 integer       no
     machdep.cpu.thread_count			 integer       no
     machdep.cpu.tlb.data.large 		 integer       no
     machdep.cpu.tlb.data.large_level1		 integer       no
     machdep.cpu.tlb.data.small 		 integer       no
     machdep.cpu.tlb.data.small_level1		 integer       no
     machdep.cpu.tlb.inst.large 		 integer       no
     machdep.cpu.tlb.inst.small 		 integer       no
     machdep.cpu.tlb.shared			 integer       no
     machdep.cpu.ucupdate			 integer       yes
     machdep.cpu.vendor 			 string        no
     machdep.cpu.xsave.extended_state		 integer       no
     machdep.tsc.deep_idle_rebase		 integer       yes
     machdep.tsc.frequency			 integer       no
     machdep.tsc.nanotime.generation		 integer       no
     machdep.tsc.nanotime.shift 		 integer       no
     net.inet.ip.forwarding			 integer       yes
     net.inet.ip.portrange.first		 integer       yes
     net.inet.ip.portrange.hifirst		 integer       yes
     net.inet.ip.portrange.hilast		 integer       yes
     net.inet.ip.portrange.last 		 integer       yes
     net.inet.ip.portrange.lowfirst		 integer       yes
     net.inet.ip.portrange.lowlast		 integer       yes
     net.inet.ip.redirect			 integer       yes
     net.inet.ip.ttl				 integer       yes
     net.inet.udp.checksum			 integer       yes
     net.inet.udp.maxdgram			 integer       yes
     vm.loadavg 				 struct        no
     vm.swapusage				 struct        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.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
     user.stream_max				 integer       no
     user.tzname_max				 integer       no

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 identifiers
     <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

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 per uid to 1000, one would use the following request:

	   sysctl kern.maxprocperuid=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

     More variables than these exist, and the best and likely only place to search for their deeper meaning is undoubtedly the source where they
     are defined.

COMPATIBILITY

     The -w option has been deprecated and is silently ignored.

SEE ALSO

     sysctl(3), sysctl.conf(5)

HISTORY

     A sysctl utility first appeared in 4.4BSD.

     In FreeBSD 2.2, sysctl was significantly remodeled.

BSD
								 January 17, 2011							       BSD