sysctl.d
systemd
Developer
Lennart
Poettering
lennart@poettering.net
sysctl.d
5
sysctl.d
Configure kernel parameters at boot
/etc/sysctl.d/*.conf
/run/sysctl.d/*.conf
/usr/lib/sysctl.d/*.conf
Description
At boot,
systemd-sysctl.service8
reads configuration files from the above directories
to configure
sysctl8
kernel parameters.
Configuration Format
The configuration files 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 label
separators within sysctl variable
names. kernel.domainname=foo and
kernel/domainname=foo hence are
entirely equivalent.
Each configuration file shall be named in the
style of program.conf.
Files in /etc/ override files
with the same name in /usr/lib/
and /run/. Files in
/run/ override files with the same
name in /usr/lib/. Packages
should install their configuration files in
/usr/lib/. Files in
/etc/ are reserved for the local
administrator, who may use this logic to override the
configuration files installed by vendor packages. All
configuration files are sorted by their filename in
lexicographic order, regardless of which of the
directories they reside in. If multiple files specify the
same variable name, the entry in the file with the
lexicographically latest name will be applied. It is
recommended to prefix all filenames with a two-digit
number and a dash, to simplify the ordering of the
files.
If the administrator wants to disable a
configuration file supplied by the vendor, the
recommended way is to place a symlink to
/dev/null in
/etc/sysctl.d/ bearing the
same filename.
The settings configured with
sysctl.d files will be applied
early on boot. The network interface-specific options
will also be applied individually for each network
interface as it shows up in the system. (More
specifically, that is
net.ipv4.conf.*,
net.ipv6.conf.*,
net.ipv4.neigh.* and net.ipv6.neigh.*)
Example
/etc/sysctl.d/domain-name.conf example:
# Set kernel YP domain name
kernel.domainname=example.com
See Also
systemd1,
systemd-sysctl.service8,
systemd-delta1,
sysctl8,
sysctl.conf5