systemd.timer — Timer unit configuration
timer.timer
A unit configuration file whose name ends in
".timer" encodes information about
a timer controlled and supervised by systemd, for
timer-based activation.
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=, OnUnitInactiveSec=¶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.
OnCalendar=¶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.
Unit=¶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.