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 un‐
       der /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 ac‐
	      cepted 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 option.

       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)