systemd.timer - Timer unit configuration
A unit configuration file whose name ends in ".timer" encodes
information about a timer controlled and supervised by systemd, for
This man page lists the configuration options specific to this unit
type. See systemd.unit(5) for the common options of all unit
configuration files. The common configuration items are configured in
the generic [Unit] and [Install] sections. The timer specific
configuration options are configured in the [Timer] section.
For each timer file, a matching unit file must exist, describing the
unit to activate when the timer elapses. By default, a service by the
same name as the timer (except for the suffix) is activated. Example: a
timer file foo.timer activates a matching service foo.service. The unit
to activate may be controlled by Unit= (see below).
Unless DefaultDependencies= is set to false, timer units will
implicitly have dependencies of type Conflicts= and Before= on
shutdown.target. These ensure that timer units are stopped cleanly
prior to system shutdown. Only timer units involved with early boot or
late system shutdown should disable this option.
Timer files must include a [Timer] section, which carries information
about the timer it defines. The options specific to the [Timer] section
of timer units are the following:
OnActiveSec=, OnBootSec=, OnStartupSec=, OnUnitActiveSec=,
Defines monotonic timers relative to different starting points:
OnActiveSec= defines a timer relative to the moment the timer
itself is activated. OnBootSec= defines a timer relative to when
the machine was booted up. OnStartupSec= defines a timer relative
to when systemd was first started. OnUnitActiveSec= defines a
timer relative to when the unit the timer is activating was last
activated. OnUnitInactiveSec= defines a timer relative to when the
unit the timer is activating was last deactivated.
Multiple directives may be combined of the same and of different
types. For example, by combining OnBootSec= and OnUnitActiveSec=,
it is possible to define a timer that elapses in regular intervals
and activates a specific service each time.
The arguments to the directives are time spans configured in
seconds. Example: "OnBootSec=50" means 50s after boot-up. The
argument may also include time units. Example: "OnBootSec=5h 30min"
means 5 hours and 30 minutes after boot-up. For details about the
syntax of time spans see systemd.unit(5).
If a timer configured with OnBootSec= or OnStartupSec= is already
in the past when the timer unit is activated, it will immediately
elapse and the configured unit is started. This is not the case for
timers defined in the other directives.
These are monotonic timers, independent of wall-clock time and
timezones. If the computer is temporarily suspended, the monotonic
clock stops too.
If the empty string is assigned to any of these options, the list
of timers is reset, and all prior assignments will have no effect.
Defines realtime (i.e. wallclock) timers via calendar event
expressions. See systemd.time(7) for more information on the syntax
of calendar event expressions. Otherwise the semantics are similar
to OnActiveSec= and related settings.
The unit to activate when this timer elapses. The argument is a
unit name, whose suffix is not ".timer". If not specified, this
value defaults to a service that has the same name as the timer
unit, except for the suffix. (See above.) It is recommended that
the unit name that is activated and the unit name of the timer unit
are named identically, except for the suffix.
systemd(1), systemctl(8), systemd.unit(5), systemd.service(5),