## Name

sysctl.d — Configure kernel parameters at boot

## Synopsis

`/usr/lib/sysctl.d/*.conf`

`/etc/sysctl.d/*.conf`

`/run/sysctl.d/*.conf`

## Description

systemd uses configuration files from the above directories to configure sysctl(8) kernel parameters to load during boot.

## Configuration Format

The configuration files should simply contain a list of variable assignments, separated by newlines. Empty lines and lines whose first non-whitespace character is # or ; are ignored.

Note that both / and . are accepted as separators in sysctl variable names.

Each configuration file is named in the style of `<program>.conf`. Files in `/etc/` overwrite files with the same name in `/usr/lib/`. Files in `/run` overwrite files with the same name in `/etc/` and `/usr/lib/`. Packages should install their configuration files in `/usr/lib/`, files in `/etc/` are reserved for the local administration, which possibly decides to overwrite the configurations installed from packages. All files are sorted by filename in alphabetical order, regardless in which of the directories they reside, to ensure that a specific configuration file takes precedence over another file with an alphabetically later name.

## Example

Example 1. /etc/sysctl.d/domain-name.conf example:

    # Set kernel YP domain name
    kernel.domainname=example.com

## See Also

systemd(1), sysctl(8), sysctl.conf(5)