Provided by: systemd_204-5ubuntu20.31_amd64 
NAME
systemd.timer - Timer unit configuration
SYNOPSIS
timer.timer
DESCRIPTION
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.
OPTIONS
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.
SEE ALSO
systemd(1), systemctl(8), systemd.unit(5), systemd.service(5), systemd.time(7), systemd.directives(7)