# phpman > man > SYSCTL(8)

[SYSCTL(8)](https://www.chedong.com/phpMan.php/man/SYSCTL/8/markdown)                               System Administration                              [SYSCTL(8)](https://www.chedong.com/phpMan.php/man/SYSCTL/8/markdown)



## 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  pro‐
              grammable 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 --load
              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 speci‐
              fied.  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. 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 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

### -r --pattern
              Only apply settings that match _pattern_.  The _pattern_ uses extended regular  expression
              syntax.

### -A -a

### -d -h

### -f -p

### -X -a

### -o

### -x

### -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.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
       [**sysctl.conf**(5)](https://www.chedong.com/phpMan.php/man/sysctl.conf/5/markdown) [**regex**(7)](https://www.chedong.com/phpMan.php/man/regex/7/markdown)

## AUTHOR
       George Staikos ⟨<staikos@0wned.org>⟩

## REPORTING BUGS
       Please send bug reports to ⟨<procps@freelists.org>⟩



procps-ng                                    2020-02-27                                    [SYSCTL(8)](https://www.chedong.com/phpMan.php/man/SYSCTL/8/markdown)