SYSCTL(8)                    System Administration                   SYSCTL(8)

       sysctl - configure kernel parameters at runtime

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

       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.

              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.   This  requires  the  -w
              parameter to use.

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

       -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.

       -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.

       /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


       sysctl.conf(5) regex(7)

       George Staikos <>

       Please send bug reports to <>

procps-ng                          Jan 2012                          SYSCTL(8)
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