Systemd
Table of Contents
1. Cheat sheet
1.1. Reload the set of units after editing files
systemctl daemon-reload
1.2. List units
systemctl list-units
1.3. List unit files
systemctl list-unit-files
1.4. View a unit file's content
systemctl cat UNIT
1.5. Override a unit's attribute
This will create a UNIT.d/override.conf file (and directory). See Units can be overridden.
systemctl edit UNIT
2. Systemd Units
- a
unitis any resource that systemd knows how to manage - units are defined in
unit files
2.1. Units can be overridden
- either fully, by providing a unit file with the same name, but at a location that takes precedence
- or partially, by creating a directory with the same name of the
unit, with an extra suffix
.d, and putting.conffiles in that directory
2.2. Types of units
2.2.1. .automount
2.2.2. .device
2.2.3. .mount
2.2.4. .path
2.2.5. .scope
2.2.6. .service
2.2.7. .slice
2.2.8. .snapshot
2.2.9. .socket
2.2.10. .swap
2.2.11. .target
Targets are used as a synchronization mechanism between units.
2.2.12. .timer
3. Systemd Generators
- generators are executable that are run before any service is started
- generators are used mainly for backward compatibility (e.g. to process rc.local into a systemd unit).
4. Symbolic link farms
Systemd uses directories containing symlinks to store data about the
units. For example there are *.wants/ and *.requires/ directories
to denote dependency relationships between units.
5. Other resources
6. Backlinks
- Related notes (cheatsheet.org)