Manual: sysctl

SYSCTL(8)					    System Administration					   SYSCTL(8)

NAME
       sysctl - configure kernel parameters at runtime

SYNOPSIS
       sysctl [options] [variable[=value]] [...]
       sysctl -p [file or regexp] [...]

DESCRIPTION
       sysctl  is  used to modify kernel parameters at runtime.	 The parameters available are those listed under /proc/sys/.
       Procfs is required for sysctl support in Linux.	You can use sysctl to both read and write sysctl data.

PARAMETERS
       variable
	      The name of a key to read from.  An example is kernel.ostype.  The '/' separator is also accepted in place  of
	      a '.'.

       variable=value
	      To  set  a key, use the form variable=value where variable is the key and value is the value to set it to.  If
	      the value contains quotes or characters which are parsed by the shell, you may need to enclose  the  value  in
	      double quotes.

       -n, --values
	      Use this option to disable printing of the key name when printing values.

       -e, --ignore
	      Use this option to ignore errors about unknown keys.

       -N, --names
	      Use this option to only print the names.	It may be useful with shells that have programmable completion.

       -q, --quiet
	      Use this option to not display the values set to stdout.

       -w, --write
	      Force all arguments to be write arguments and print an error if they cannot be parsed this way.

       -p[FILE], --load[=FILE]
	      Load  in	sysctl settings from the file specified or /etc/sysctl.conf if none given.  Specifying - as filename
	      means reading data from standard input. Using this option will mean arguments to sysctl are files,  which	 are
	      read in the order they are specified.  The file argument may be specified as regular expression.

       -a, --all
	      Display all values currently available except deprecated and verboten parameters.

       --deprecated
	      Include deprecated parameters to --all values listing.

       -b, --binary
	      Print value without new line.

       --system
	      Load settings from all system configuration files. See the System file precedence sub-section below.

       -r, --pattern pattern
	      Only apply settings that match pattern.  The pattern uses extended regular expression syntax.

       -A     Alias of -a

       -d     Alias of -h

       -f     Alias of -p

       -X     Alias of -a

       -o     Does nothing, exists for BSD compatibility.

       -x     Does nothing, exists for BSD compatibility.

       -h, --help
	      Display help text and exit.

       -V, --version
	      Display version information and exit.

FILES
       /proc/sys
       /etc/sysctl.d/*.conf
       /run/sysctl.d/*.conf
       /usr/local/lib/sysctl.d/*.conf
       /usr/lib/sysctl.d/*.conf
       /lib/sysctl.d/*.conf
       /etc/sysctl.conf

NOTES
   System file precedence
       When using the --system option, sysctl will read files from directories in the following list in given order from top
       to bottom. Once a file of a given filename is loaded, any file of the same name in subsequent directories is ignored.

       /etc/sysctl.d/*.conf
       /run/sysctl.d/*.conf
       /usr/local/lib/sysctl.d/*.conf
       /usr/lib/sysctl.d/*.conf
       /lib/sysctl.d/*.conf
       /etc/sysctl.conf

       All  configuration files are sorted in lexicographic order, regardless of the directory they reside in. Configuration
       files can either be completely replaced (by having a new configuration file with the same  name	in  a  directory  of
       higher priority) or partially replaced (by having a configuration file that is ordered later).

   Deprecated parameters
       The  base_reachable_time and retrans_time are deprecated.  The sysctl command does not allow changing values of these
       parameters.  Users who insist to use deprecated kernel interfaces should push values to /proc file  system  by  other
       means.  For example:

       echo 256 > /proc/sys/net/ipv6/neigh/eth0/base_reachable_time

   Verboten parameters
       Certain	kernel	parameters  should not be read due to side-effects and will be skipped by sysctl using the --all op‐
       tion.

       stat_refresh
	      This parameter returns no value but flushes per-cpu vm statistics.

EXAMPLES
       /sbin/sysctl -a
       /sbin/sysctl -n kernel.hostname
       /sbin/sysctl -w kernel.domainname="example.com"
       /sbin/sysctl -p/etc/sysctl.conf
       /sbin/sysctl -a --pattern forward
       /sbin/sysctl -a --pattern forward$
       /sbin/sysctl -a --pattern 'net.ipv4.conf.(eth|wlan)0.arp'
       /sbin/sysctl --pattern '^net.ipv6' --system

SEE ALSO
       proc(5), sysctl.conf(5), regex(7)

REPORTING BUGS
       Please send bug reports to procps@freelists.org

procps-ng						 2024-07-19						   SYSCTL(8)