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.

       --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
              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.

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).

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

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

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

SEE ALSO

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

AUTHOR

       George Staikos ⟨staikos@0wned.org⟩

REPORTING BUGS

       Please send bug reports to ⟨procps@freelists.org⟩