sysctl(8) — Linux manual page


SYSCTL(8)                   System Administration                  SYSCTL(8)

NAME         top

       sysctl - configure kernel parameters at runtime

SYNOPSIS         top

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

DESCRIPTION         top

       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         top

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

              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
              Use this option when all arguments prescribe a key to be set.

       -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.

              Include deprecated parameters to --all values listing.

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

              Load settings from all system configuration files. Files are
              read 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

       -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.

EXAMPLES         top

       /sbin/sysctl -a
       /sbin/sysctl -n kernel.hostname
       /sbin/sysctl -w kernel.domainname=""
       /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 --system --pattern '^net.ipv6'


       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

FILES         top


SEE ALSO         top

       sysctl.conf(5) regex(7)

AUTHOR         top

       George Staikos ⟨⟩

REPORTING BUGS         top

       Please send bug reports to ⟨⟩

COLOPHON         top

       This page is part of the procps-ng (/proc filesystem utilities)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for
       this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-08-13.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-07-29.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

procps-ng                        2020-02-27                        SYSCTL(8)

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