noble (3) Config::Model::models::Systemd::Section::Timer.3pm.gz
NAME
Config::Model::models::Systemd::Section::Timer - Configuration class Systemd::Section::Timer
DESCRIPTION
Configuration classes used by Config::Model
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).
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 "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 parse-man.pl <https://github.com/dod38fr/config-model-systemd/contrib/parse-man.pl>
Elements
OnActiveSec
Defines monotonic timers relative to different starting points:
Multiple directives may be combined of the same and of different types, in which case the timer unit will
trigger whenever any of the specified timer expressions elapse. 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. Moreover, both monotonic time expressions and "OnCalendar" calendar
expressions may be combined in the same timer unit.
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.time(7).
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 generally pauses, too. Note that if "WakeSystem" is used, a different
monotonic clock is selected that continues to advance while the system is suspended and thus can be used
as the trigger to resume the system.
If the empty string is assigned to any of these options, the list of timers is reset (both monotonic
timers and "OnCalendar" timers, see below), 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 "AccuracySec" setting below. Optional. Type uniline.
OnBootSec
Defines monotonic timers relative to different starting points:
Multiple directives may be combined of the same and of different types, in which case the timer unit will
trigger whenever any of the specified timer expressions elapse. 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. Moreover, both monotonic time expressions and "OnCalendar" calendar
expressions may be combined in the same timer unit.
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.time(7).
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 generally pauses, too. Note that if "WakeSystem" is used, a different
monotonic clock is selected that continues to advance while the system is suspended and thus can be used
as the trigger to resume the system.
If the empty string is assigned to any of these options, the list of timers is reset (both monotonic
timers and "OnCalendar" timers, see below), 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 "AccuracySec" setting below. Optional. Type uniline.
OnStartupSec
Defines monotonic timers relative to different starting points:
Multiple directives may be combined of the same and of different types, in which case the timer unit will
trigger whenever any of the specified timer expressions elapse. 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. Moreover, both monotonic time expressions and "OnCalendar" calendar
expressions may be combined in the same timer unit.
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.time(7).
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 generally pauses, too. Note that if "WakeSystem" is used, a different
monotonic clock is selected that continues to advance while the system is suspended and thus can be used
as the trigger to resume the system.
If the empty string is assigned to any of these options, the list of timers is reset (both monotonic
timers and "OnCalendar" timers, see below), 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 "AccuracySec" setting below. Optional. Type uniline.
OnUnitActiveSec
Defines monotonic timers relative to different starting points:
Multiple directives may be combined of the same and of different types, in which case the timer unit will
trigger whenever any of the specified timer expressions elapse. 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. Moreover, both monotonic time expressions and "OnCalendar" calendar
expressions may be combined in the same timer unit.
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.time(7).
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 generally pauses, too. Note that if "WakeSystem" is used, a different
monotonic clock is selected that continues to advance while the system is suspended and thus can be used
as the trigger to resume the system.
If the empty string is assigned to any of these options, the list of timers is reset (both monotonic
timers and "OnCalendar" timers, see below), 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 "AccuracySec" setting below. Optional. Type uniline.
OnUnitInactiveSec
Defines monotonic timers relative to different starting points:
Multiple directives may be combined of the same and of different types, in which case the timer unit will
trigger whenever any of the specified timer expressions elapse. 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. Moreover, both monotonic time expressions and "OnCalendar" calendar
expressions may be combined in the same timer unit.
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.time(7).
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 generally pauses, too. Note that if "WakeSystem" is used, a different
monotonic clock is selected that continues to advance while the system is suspended and thus can be used
as the trigger to resume the system.
If the empty string is assigned to any of these options, the list of timers is reset (both monotonic
timers and "OnCalendar" timers, see below), 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 "AccuracySec" setting below. Optional. Type uniline.
OnCalendar
Defines realtime (i.e. wallclock) timers with 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.
Note that timers do not necessarily expire at the precise time configured with this setting, as it is
subject to the "AccuracySec" setting below.
May be specified more than once, in which case the timer unit will trigger whenever any of the specified
expressions elapse. Moreover calendar timers and monotonic timers (see above) may be combined within the
same timer unit.
If the empty string is assigned to any of these options, the list of timers is reset (both "OnCalendar"
timers and monotonic timers, see above), and all prior assignments will have no effect.
Note that calendar timers might be triggered at unexpected times if the system's realtime clock is not
set correctly. Specifically, on systems that lack a battery-buffered Realtime Clock (RTC) it might be
wise to enable "systemd-time-wait-sync.service" to ensure the clock is adjusted to a network time source
before the timer event is set up. Timer units with at least one "OnCalendar" expression are automatically
ordered after "time-sync.target", which "systemd-time-wait-sync.service" is ordered before.
When a system is temporarily put to sleep (i.e. system suspend or hibernation) the realtime clock does
not pause. When a calendar timer elapses while the system is sleeping it will not be acted on
immediately, but once the system is later resumed it will catch up and process all timers that triggered
while the system was sleeping. Note that if a calendar timer elapsed more than once while the system was
continuously sleeping the timer will only result in a single service activation. If "WakeSystem" (see
below) is enabled a calendar time event elapsing while the system is suspended will cause the system to
wake up (under the condition the system's hardware supports time-triggered wake-up functionality).
Optional. Type list of uniline.
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 "OnCalendar", "OnActiveSec", "OnBootSec",
"OnStartupSec", "OnUnitActiveSec" or "OnUnitInactiveSec" and ending the time configured with
"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 systemd-system.conf(5)'s
"TimerSlackNSec" setting. See prctl(2) for details. To optimize power consumption, make sure to set this
value as high as possible and as low as necessary.
Note that this setting is primarily a power saving option that allows coalescing CPU wake-ups. It should
not be confused with "RandomizedDelaySec" (see below) which adds a random value to the time the timer
shall elapse next and whose purpose is the opposite: to stretch elapsing of timer events over a longer
period to reduce workload spikes. For further details and explanations and how both settings play
together, see below. Optional. Type uniline.
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 before each iteration, and the delay will simply be added on top of the
next determined elapsing time, unless modified with "FixedRandomDelay", see below.
This setting is useful to stretch dispatching of similarly configured timer events over a certain time
interval, to prevent them from firing all at the same time, possibly resulting in resource congestion.
Note the relation to "AccuracySec" above: the latter allows the service manager to coalesce timer events
within a specified time range in order to minimize wakeups, while this setting does the opposite: it
stretches timer events over an interval, to make it unlikely that they fire simultaneously. If
"RandomizedDelaySec" and "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 "AccuracySec" defaults to 1 minute and "RandomizedDelaySec" to 0, thus
encouraging coalescing of timer events. In order to optimally stretch timer events over a certain range
of time, set "AccuracySec=1us" and "RandomizedDelaySec" to some higher value. Optional. Type uniline.
FixedRandomDelay
Takes a boolean argument. When enabled, the randomized offset specified by "RandomizedDelaySec" is reused
for all firings of the same timer. For a given timer unit, the offset depends on the machine ID, user
identifier and timer name, which means that it is stable between restarts of the manager. This
effectively creates a fixed offset for an individual timer, reducing the jitter in firings of this timer,
while still avoiding firing at the same time as other similarly configured timers.
This setting has no effect if "RandomizedDelaySec" is set to 0. Defaults to "false". Optional. Type
boolean.
OnClockChange
These options take boolean arguments. When true, the service unit will be triggered when the system clock
("CLOCK_REALTIME") jumps relative to the monotonic clock ("CLOCK_MONOTONIC"), or when the local system
timezone is modified. These options can be used alone or in combination with other timer expressions (see
above) within the same timer unit. These options default to "false". Optional. Type uniline.
OnTimezoneChange
These options take boolean arguments. When true, the service unit will be triggered when the system clock
("CLOCK_REALTIME") jumps relative to the monotonic clock ("CLOCK_MONOTONIC"), or when the local system
timezone is modified. These options can be used alone or in combination with other timer expressions (see
above) within the same timer unit. These options default to "false". Optional. Type uniline.
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. Optional. Type uniline.
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. Such triggering is nonetheless subject to the
delay imposed by "RandomizedDelaySec". This is useful to catch up on missed runs of the service when the
system was powered down. Note that this setting only has an effect on timers configured with
"OnCalendar". Defaults to "false".
Use systemctl clean --what=state X on the timer unit to remove the timestamp file maintained by this
option from disk. In particular, use this command before uninstalling a timer unit. See systemctl(1) for
details. Optional. Type boolean.
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 "false".
Note that this functionality requires privileges and is thus generally only available in the system
service manager.
Note that behaviour of monotonic clock timers (as configured with "OnActiveSec", "OnBootSec",
"OnStartupSec", "OnUnitActiveSec", "OnUnitInactiveSec", see above) is altered depending on this option.
If false, a monotonic clock is used that is paused during system suspend ("CLOCK_MONOTONIC"), if true a
different monotonic clock is used that continues advancing during system suspend ("CLOCK_BOOTTIME"), see
clock_getres(2) for details. Optional. Type boolean.
RemainAfterElapse
Takes a boolean argument. If true, a timer will stay loaded, and its state remains queryable even after
it elapsed and the associated unit (as configured with "Unit", see above) deactivated again. If false, an
elapsed timer unit that cannot elapse anymore is unloaded once its associated unit deactivated again.
Turning this off is particularly useful for transient timer units. Note that this setting has an effect
when repeatedly starting a timer unit: if "RemainAfterElapse" is on, starting the timer a second time has
no effect. However, if "RemainAfterElapse" is off and the timer unit was already unloaded, it can be
started again, and thus the service can be triggered multiple times. Defaults to "true". Optional. Type
boolean.
SEE ALSO
• cme
COPYRIGHT
2010-2016 Lennart Poettering and others
2016 Dominique Dumont
LICENSE
LGPLv2.1+