.\"
.\" Copyright (c) 2016-2023 Jim Warner <james.warner@comcast.net>
.\" Copyright (c) 2019-2023 Craig Small <csmall@dropbear.xyz>
.\" Copyright (c) 2011-2012 Sami Kerola <kerolasa@iki.fi>
.\" Copyright (c) 1999      George Staikos <staikos@0wned.org>
.\"
.\" This program is free software; you can redistribute it and/or modify
.\" it under the terms of the GNU General Public License as published by
.\" the Free Software Foundation; either version 2 of the License, or
.\" (at your option) any later version.
.\"
.\"
.TH SYSCTL.CONF "5" "2021-09-15" "procps-ng" "File Formats"
.SH NAME
sysctl.conf \- sysctl preload/configuration file
.SH DESCRIPTION
.B sysctl.conf
is a simple file containing sysctl values to be read in and set by
.BR sysctl .
The syntax is simply as follows:
.RS
.sp
.nf
.ne 7
# comment
; comment

token = value
.fi
.RE
.PP
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 \fI#\fR or \fI;\fR are considered comments and ignored.

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

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

Maximum supported line length of the value is 4096 characters due
to a limitation of \fI/proc\fR entries in Linux kernel.
.SH EXAMPLE
.RS
.sp
.nf
.ne 7
# sysctl.conf sample
#
  kernel.domainname = example.com
; this one has a space which will be written to the sysctl!
  kernel.modprobe = /sbin/mod probe
.fi
.RE
.PP
.SH FILES
.I /etc/sysctl.d/*.conf
.br
.I /run/sysctl.d/*.conf
.br
.I /usr/local/lib/sysctl.d/*.conf
.br
.I /usr/lib/sysctl.d/*.conf
.br
.I /lib/sysctl.d/*.conf
.br
.I /etc/sysctl.conf

The paths where
.B sysctl
preload files usually exist.  See also
.B sysctl
option
.IR \-\-system .
.SH SEE ALSO
.BR sysctl (8)
.SH AUTHOR
.UR staikos@0wned.org
George Staikos
.UE
.SH "REPORTING BUGS"
Please send bug reports to
.UR procps@freelists.org
.UE