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sysctl(8) [mojave man page]

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

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