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.


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 =
; this one has a space which will be written to the sysctl!
  kernel.modprobe = /sbin/mod probe



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

See Also



George Staikos

Reporting Bugs

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Referenced By

sysctl(8), sysctl.d(5), ufw(8), ufw-framework(8).

January 2012 procps-ng File Formats