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This is separate from sysctl.rta which is for the network stack and will be retained.
Isysctl.rta is for the DRTOS I/O process. Eventually features will be merged into one utility.


isysctl -- get or set state of the I/O system process


isysctl [-bdehiNnoTtqWx] [-B bufsize] [-f filename]      name[=value[,value]] ...
isysctl [-bdehNnoTtqWx] [-B bufsize] -a


The isysctl 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 command 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.


Set the buffer size to read from the isysctl to bufsize.  This is necessary for a isysctl that has variable length, and the probe value of 0 is a valid length, such  as kern.arandom.

-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.


Specify a file which contains a pair of name and value in each line.  isysctl reads and processes the specified file first      and then processes the name and value pairs in the command line argument.

-h Format output for human, rather than machine, readability.
-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 Do not show variable 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.
-T Display only variables that are settable via loader (CTLFLAG_TUN).
-t Print the type of the variable.
-W Display only writable variables that are not statistical. Useful for determining the set of runtime tunable sysctls.
-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 isysctl consists of integers, strings, and opaque types. The isysctl utility only knows about a couple of opaque types, and will resort to hexdumps for the rest.

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
kern.ostype string no
kern.osrelease string no
kern.osrevision integer no
kern.version string no
kern.maxvnodes integer yes
kern.maxproc integer no
kern.maxprocperuid integer yes
kern.maxfiles integer yes
kern.maxfilesperproc integer yes
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.boottime struct no
kern.domainname string yes
kern.filedelay integer yes
kern.dirdelay integer yes
kern.metadelay integer yes
kern.osreldate integer no
kern.bootfile string yes
kern.corefile string yes
kern.logsigexit integer yes
security.bsd.suser_enabled integer yes
security.bsd.see_other_uids integer yes
security.bsd.unprivileged_proc_debug integer yes
security.bsd.unprivileged_read_msgbuf integer yes
vm.loadavg struct no
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.floatingpoint integer no
hw.machine_arch string no
hw.realmem integer no
machdep.adjkerntz integer yes
machdep.disable_rtc_set integer yes
machdep.guessed_bootdev 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
user.stream_max integer no
user.tzname_max integer no
user.localbase string no


The isysctl utility exits 0 on success, and >0 if an error occurs.



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


A sysctl utility first appeared in 4.4BSD.
In FreeBSD 2.2, sysctl was significantly remodeled.


The sysctl utility presently exploits an undocumented interface to the kernel sysctl facility to traverse the sysctl tree and to retrieve format and name information. This correct interface is being thought about for the time being.


INtime 7.0
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