.\" .\" Copyright (c) 2016-2023 Jim Warner .\" Copyright (c) 2019-2024 Craig Small .\" Copyright (c) 2011-2012 Sami Kerola .\" Copyright (c) 1999 George Staikos .\" .\" 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 2024-10-24 procps-ng .SH NAME sysctl.conf \- Linux kernel configuration parameters .SH DESCRIPTION .B sysctl.conf is a set of configuration files that contain Linux kernel configuration parameters to be read and set by .BR sysctl (8). .PP This man page describes the configuration files for .I procps .BR sysctl . If you are using .BR systemd\-sysctl (8), refer to .BR sysctl.d (5) and note that it won't use the file .IR \%/etc/\:\%sysctl\:\%.conf . .SS "Configuration Format" Each line of a file read by .I procps .B sysctl describes a kernel parameter in the following format. .P .RS .EX token = value .EE .RE .P Blank lines and lines that start with .RB \[lq] # \[rq] or .RB \[lq] ; \[rq] are ignored. .P If a line begins with a single .RB \[lq] \- \[rq], a failing attempt to set the value is ignored. .SH FILES .I procps .BR sysctl , when run with the .B \%\-\-system option, reads files from directories in the order shown below. .P .RS .TP .IR /etc/sysctl.d/ * .conf .TQ .IR /run/sysctl.d/ * .conf .TQ .IR /usr/local/lib/sysctl.d/ * .conf .TQ .IR /usr/lib/sysctl.d/ * .conf .TQ .IR /lib/sysctl.d/ * .conf .RE .P Finally, .I procps .B sysctl reads .IR \%/etc/\:\%sysctl\:\%.conf . This file is not used by .BR systemd\-sysctl , which means that some kernel parameters are not set depending on the implementation of .B sysctl that is installed. .SH BUGS The maximum supported length of .I value is 4096 characters due to a limitation on .I /proc entry length in the Linux kernel. .SH EXAMPLES .EX # # kernel.domainname = example.com ; A value containing a space is written to the sysctl. kernel.modprobe = /sbin/mod probe .EE .SH "SEE ALSO" .BR sysctl.d (5), .BR sysctl (8), .BR systemd\-sysctl (8)