2.11BSD#431 - /usr/man/cat8/sysctl.0

SYSCTL(8)	    UNIX Programmer'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 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 -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 suppressed and that only its value should be out-
     put.  This flag is useful for setting shell variables.  For
     example, to save the pagesize in variable 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 information is sum-
     maried 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.acctthresh	   int	     yes
	  kern.ostype		   string    no
	  kern.osrelease	   string    no
	  kern.osrevision	   long      no
	  kern.version		   string    no
	  kern.maxinodes	   integer   no
	  kern.maxproc		   integer   no
	  kern.maxfiles            integer   no
	  kern.maxtext		   integer   no
	  kern.argmax		   integer   no
	  kern.securelevel	   integer   raise only


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SYSCTL(8)	    UNIX Programmer's Manual		SYSCTL(8)


	  kern.hostname            string    yes
	  kern.hostid		   long      yes
	  kern.clockrate	   struct    no
	  kern.posix1version	   integer   no
	  kern.ngroups		   integer   no
	  kern.job_control	   integer   no
	  kern.saved_ids	   integer   no
	  kern.boottime            struct    no
	  vm.loadavg		   struct    no
	  machdep.console_device   dev_t     no
	  machdep.mscp.printf	   integer   yes
	  machdep.tmscp.cache	   integer   yes
	  machdep.tmscp.printf	   integer   yes
	  net.inet.ip.forwarding   integer   yes
	  net.inet.ip.redirect	   integer   yes
	  net.inet.ip.ttl	   integer   yes
	  net.inet.icmp.maskrepl   integer   yes
	  net.inet.udp.checksum    integer   yes
	  hw.machine		   string    no
	  hw.model		   string    no
	  hw.ncpu		   integer   no
	  hw.byteorder		   integer   no
	  hw.physmem		   long      no
	  hw.usermem		   long      no
	  hw.pagesize		   integer   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

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 hostname of the system to foo.bar.com, one would
     use the follow request:


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SYSCTL(8)	    UNIX Programmer's Manual		SYSCTL(8)


	       sysctl -w kern.hostname=foo.bar.com

     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 identif-
		    iers

     <sys/gmon.h>   definitions for third level profiling iden-
		    tifiers

     <machine/cpu.h>
		    definitions for second and third level
		    machine dependent identifiers

     <sys/vmparam.h>
		    definitions for second level virtual memory
		    identifiers

     <netinet/in.h> definitions for third level Internet identif-
		    iers 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.


Printed 11/24/99	 April 24, 1999                         3