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 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)