Sysctl

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.  This
             requires the -w parameter to use.

      -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 you want to change a sysctl setting.

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

      -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

      /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 --system --pattern '^net.ipv6'

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.conf