# PODNAME: Config::Model::models::Systemd::Section::Timer
# ABSTRACT:  Configuration class Systemd::Section::Timer

=encoding utf8

=head1 NAME

Config::Model::models::Systemd::Section::Timer - Configuration class Systemd::Section::Timer

=head1 DESCRIPTION

Configuration classes used by L<Config::Model>

A unit configuration file whose name ends in
C<.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
L<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 C<Unit> (see below).

Note that in case the unit to activate is already active at the time the timer elapses it is not restarted,
but simply left running. There is no concept of spawning new service instances in this case. Due to this, services
with C<RemainAfterExit> set (which stay around continuously even after the service's main process
exited) are usually not suitable for activation via repetitive timers, as they will only be activated once, and
then stay around forever.
This configuration class was generated from systemd documentation.
by L<parse-man.pl|https://github.com/dod38fr/config-model-systemd/contrib/parse-man.pl>


=head1 Elements

=head2 OnActiveSec

Defines monotonic timers relative to different
starting points: C<OnActiveSec> defines a
timer relative to the moment the timer itself is activated.
C<OnBootSec> defines a timer relative to when
the machine was booted up. C<OnStartupSec>
defines a timer relative to when systemd was first started.
C<OnUnitActiveSec> defines a timer relative
to when the unit the timer is activating was last activated.
C<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
C<OnBootSec> and
C<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
L<systemd.time(7)>.

If a timer configured with C<OnBootSec>
or C<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.

Note that timers do not necessarily expire at the
precise time configured with these settings, as they are
subject to the C<AccuracySec> setting
below. I< Optional. Type uniline.  > 

=head2 OnBootSec

Defines monotonic timers relative to different
starting points: C<OnActiveSec> defines a
timer relative to the moment the timer itself is activated.
C<OnBootSec> defines a timer relative to when
the machine was booted up. C<OnStartupSec>
defines a timer relative to when systemd was first started.
C<OnUnitActiveSec> defines a timer relative
to when the unit the timer is activating was last activated.
C<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
C<OnBootSec> and
C<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
L<systemd.time(7)>.

If a timer configured with C<OnBootSec>
or C<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.

Note that timers do not necessarily expire at the
precise time configured with these settings, as they are
subject to the C<AccuracySec> setting
below. I< Optional. Type uniline.  > 

=head2 OnStartupSec

Defines monotonic timers relative to different
starting points: C<OnActiveSec> defines a
timer relative to the moment the timer itself is activated.
C<OnBootSec> defines a timer relative to when
the machine was booted up. C<OnStartupSec>
defines a timer relative to when systemd was first started.
C<OnUnitActiveSec> defines a timer relative
to when the unit the timer is activating was last activated.
C<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
C<OnBootSec> and
C<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
L<systemd.time(7)>.

If a timer configured with C<OnBootSec>
or C<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.

Note that timers do not necessarily expire at the
precise time configured with these settings, as they are
subject to the C<AccuracySec> setting
below. I< Optional. Type uniline.  > 

=head2 OnUnitActiveSec

Defines monotonic timers relative to different
starting points: C<OnActiveSec> defines a
timer relative to the moment the timer itself is activated.
C<OnBootSec> defines a timer relative to when
the machine was booted up. C<OnStartupSec>
defines a timer relative to when systemd was first started.
C<OnUnitActiveSec> defines a timer relative
to when the unit the timer is activating was last activated.
C<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
C<OnBootSec> and
C<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
L<systemd.time(7)>.

If a timer configured with C<OnBootSec>
or C<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.

Note that timers do not necessarily expire at the
precise time configured with these settings, as they are
subject to the C<AccuracySec> setting
below. I< Optional. Type uniline.  > 

=head2 OnUnitInactiveSec

Defines monotonic timers relative to different
starting points: C<OnActiveSec> defines a
timer relative to the moment the timer itself is activated.
C<OnBootSec> defines a timer relative to when
the machine was booted up. C<OnStartupSec>
defines a timer relative to when systemd was first started.
C<OnUnitActiveSec> defines a timer relative
to when the unit the timer is activating was last activated.
C<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
C<OnBootSec> and
C<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
L<systemd.time(7)>.

If a timer configured with C<OnBootSec>
or C<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.

Note that timers do not necessarily expire at the
precise time configured with these settings, as they are
subject to the C<AccuracySec> setting
below. I< Optional. Type uniline.  > 

=head2 OnCalendar

Defines realtime (i.e. wallclock) timers with
calendar event expressions. See
L<systemd.time(7)>
for more information on the syntax of calendar event
expressions. Otherwise, the semantics are similar to
C<OnActiveSec> and related settings.

Note that timers do not necessarily expire at the
precise time configured with this setting, as it is subject to
the C<AccuracySec> setting
below.

May be specified more than once. I< Optional. Type list of uniline.  > 

=head2 AccuracySec

Specify the accuracy the timer shall elapse
with. Defaults to 1min. The timer is scheduled to elapse
within a time window starting with the time specified in
C<OnCalendar>,
C<OnActiveSec>,
C<OnBootSec>,
C<OnStartupSec>,
C<OnUnitActiveSec> or
C<OnUnitInactiveSec> and ending the time
configured with C<AccuracySec> later. Within
this time window, the expiry time will be placed at a
host-specific, randomized, but stable position that is
synchronized between all local timer units. This is done in
order to optimize power consumption to suppress unnecessary
CPU wake-ups. To get best accuracy, set this option to
1us. Note that the timer is still subject to the timer slack
configured via
L<systemd-system.conf(5)>'s
C<TimerSlackNSec> setting. See
L<prctl(2)>
for details. To optimize power consumption, make sure to set
this value as high as possible and as low as
necessary. I< Optional. Type uniline.  > 

=head2 RandomizedDelaySec

Delay the timer by a randomly selected, evenly
distributed amount of time between 0 and the specified time
value. Defaults to 0, indicating that no randomized delay
shall be applied. Each timer unit will determine this delay
randomly each time it is started, and the delay will simply be
added on top of the next determined elapsing time. This is
useful to stretch dispatching of similarly configured timer
events over a certain amount time, to avoid that they all fire
at the same time, possibly resulting in resource
congestion. Note the relation to
C<AccuracySec> above: the latter allows the
service manager to coalesce timer events within a specified
time range in order to minimize wakeups, the former does the
opposite: it stretches timer events over a time range, to make
it unlikely that they fire simultaneously. If
C<RandomizedDelaySec> and
C<AccuracySec> are used in conjunction, first
the randomized delay is added, and then the result is
possibly further shifted to coalesce it with other timer
events happening on the system. As mentioned above
C<AccuracySec> defaults to 1min and
C<RandomizedDelaySec> to 0, thus encouraging
coalescing of timer events. In order to optimally stretch
timer events over a certain range of time, make sure to set
C<RandomizedDelaySec> to a higher value, and
C<AccuracySec=1us>. I< Optional. Type uniline.  > 

=head2 Unit

The unit to activate when this timer elapses.
The argument is a unit name, whose suffix is not
C<.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. I< Optional. Type uniline.  > 

=head2 Persistent

Takes a boolean argument. If true, the time
when the service unit was last triggered is stored on disk.
When the timer is activated, the service unit is triggered
immediately if it would have been triggered at least once
during the time when the timer was inactive. This is useful to
catch up on missed runs of the service when the machine was
off. Note that this setting only has an effect on timers
configured with C<OnCalendar>. Defaults
to C<false>.
I< Optional. Type boolean.  > 

=head2 WakeSystem

Takes a boolean argument. If true, an elapsing
timer will cause the system to resume from suspend, should it
be suspended and if the system supports this. Note that this
option will only make sure the system resumes on the
appropriate times, it will not take care of suspending it
again after any work that is to be done is finished. Defaults
to C<false>. I< Optional. Type boolean.  > 

=head2 RemainAfterElapse

Takes a boolean argument. If true, an elapsed
timer will stay loaded, and its state remains queriable. If
false, an elapsed timer unit that cannot elapse anymore is
unloaded. Turning this off is particularly useful for
transient timer units that shall disappear after they first
elapse. Note that this setting has an effect on repeatedly
starting a timer unit that only elapses once: if
C<RemainAfterElapse> is on, it will not be
started again, and is guaranteed to elapse only once. However,
if C<RemainAfterElapse> is off, it might be
started again if it is already elapsed, and thus be triggered
multiple times. Defaults to
C<yes>. I< Optional. Type boolean.  > 

=head1 SEE ALSO

=over

=item *

L<cme>

=back

=head1 COPYRIGHT

=over

=item 2010-2016 Lennart Poettering and others

=item 2016 Dominique Dumont


=back

=head1 LICENSE

=over

=item LGPLv2.1+


=back

=cut

