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systemd-sysctl.service, systemd-sysctl - Configure kernel parameters at boot


/usr/lib/systemd/systemd-sysctl [OPTIONS...] [CONFIGFILE...]



systemd-sysctl.service is an early boot service that configures sysctl(8) kernel parameters by invoking /usr/lib/systemd/systemd-sysctl.

When invoked with no arguments, /usr/lib/systemd/systemd-sysctl applies all directives from configuration files listed in sysctl.d(5). If one or more filenames are passed on the command line, only the directives in these files are applied.

In addition, --prefix= option may be used to limit which sysctl settings are applied.

See sysctl.d(5) for information about the configuration of sysctl settings. After sysctl configuration is changed on disk, it must be written to the files in /proc/sys/ before it takes effect. It is possible to update specific settings, or simply to reload all configuration, see Examples below.



Only apply rules with the specified prefix.

Added in version 230.


Always return non-zero exit code on failure (including invalid sysctl variable name and insufficient permissions), unless the sysctl variable name is prefixed with a "-" character.

Added in version 252.


Copy the contents of config files to standard output. Before each file, the filename is printed as a comment.


Copy the contents of config files to standard output. Only the "interesting" parts of the configuration files are printed, comments and empty lines are skipped. Before each file, the filename is printed as a comment.


Do not pipe output into a pager.

-h, --help

Print a short help text and exit.


Print a short version string and exit.


systemd-sysctl supports the service credentials logic as implemented by ImportCredential=/LoadCredential=/SetCredential= (see systemd.exec(5) for details). The following credentials are used when passed in:


The contents of this credential may contain additional lines to operate on. The credential contents should follow the same format as any other sysctl.d/ drop-in configuration file. If this credential is passed it is processed after all of the drop-in files read from the file system. The settings configured in the credential hence take precedence over those in the file system.

Added in version 252.

Note that by default the systemd-sysctl.service unit file is set up to inherit the "sysctl.extra" credential from the service manager.


Example 1. Reset all sysctl settings

systemctl restart systemd-sysctl

Example 2. View coredump handler configuration

# sysctl kernel.core_pattern
kernel.core_pattern = |/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t %P %I

Example 3. Update coredump handler configuration

# /usr/lib/systemd/systemd-sysctl --prefix kernel.core_pattern

This searches all the directories listed in sysctl.d(5) for configuration files and writes /proc/sys/kernel/core_pattern.

Example 4. Update coredump handler configuration according to a specific file

# /usr/lib/systemd/systemd-sysctl 50-coredump.conf

This applies all the settings found in 50-coredump.conf. Either /etc/sysctl.d/50-coredump.conf, or /run/sysctl.d/50-coredump.conf, or /usr/lib/sysctl.d/50-coredump.conf will be used, in the order of preference.

See sysctl(8) for various ways to directly apply sysctl settings.


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

systemd 256.2