Manpages - sysctl.conf.5

sysctl.conf - sysctl preload/configuration file

sysctl.conf is a simple file containing sysctl values to be read in and set by sysctl. The syntax is simply as follows:

    # comment
    ; comment

    token = value

Note that blank lines are ignored, and whitespace before and after a token or value is ignored, although a value can contain whitespace within. Lines which begin with a # or ; are considered comments and ignored.

If a line begins with a single -, any attempts to set the value that fail will be ignored.

As the /etc/sysctl.conf file is used to override default kernel parameter values, only a small number of parameters is predefined in the file. Use /sbin/sysctl -a or follow *sysctl*(8) to list all possible parameters. The description of individual parameters can be found in the kernel documentation.

    # sysctl.conf sample
    #
      kernel.domainname = example.com
    ; this one has a space which will be written to the sysctl!
      kernel.modprobe = /sbin/mod probe

/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

The paths where sysctl preload files usually exist. See also sysctl option –system.

*sysctl*(8)

George Staikos

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