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	"plain_text": "systemd/Timers - ArchWiki\r\nArchived: 2026-04-05 17:26:02 UTC\r\nTimers are systemd unit files whose name ends in .timer that control .service files or events. Timers can be used as\r\nan alternative to cron (read #As a cron replacement). Timers have built-in support for calendar time events,\r\nmonotonic time events, and can be run asynchronously.\r\nTimer units\r\nTimers are systemd unit files with a suffix of .timer. Timers are like other unit configuration files and are loaded\r\nfrom the same paths but include a [Timer] section which defines when and how the timer activates. Timers are\r\ndefined as one of two types:\r\nRealtime timers (a.k.a. wallclock timers) activate on a calendar event, the same way that cronjobs do. The\r\noption OnCalendar= is used to define them.\r\nMonotonic timers activate after a time span relative to a varying starting point. They stop if the computer\r\nis temporarily suspended or shut down. There are number of different monotonic timers but all have the\r\nform: OnTypeSec= . Common monotonic timers include OnBootSec and OnUnitActiveSec .\r\nFor a full explanation of timer options, see the systemd.timer(5). The argument syntax for calendar events and\r\ntime spans is defined in systemd.time(7).\r\nNote systemd offers the target timers.target which sets up all timers that should be active after boot (see\r\nsystemd.special(7) for details). To use it, add WantedBy=timers.target to the [Install] section of your timer\r\nand enable the timer unit.\r\nService units\r\nFor each .timer file, a matching .service file exists (e.g. foo.timer and foo.service ). The .timer file activates\r\nand controls the .service file. The .service does not require an [Install] section as it is the timer units that are\r\nenabled. If necessary, it is possible to control a differently-named unit using the Unit= option in the timer's\r\n[Timer] section.\r\nManagement\r\nTo use a timer unit enable and start it like any other unit (remember to add the .timer suffix). To view all started\r\ntimers, run:\r\n$ systemctl list-timers\r\nNEXT LEFT LAST PASSED UNIT\r\nThu 2014-07-10 19:37:03 CEST 11h left Wed 2014-07-09 19:37:03 CEST 12h ago systemd-tmpfiles-c\r\nhttps://wiki.archlinux.org/index.php/Systemd/Timers\r\nPage 1 of 7\n\nFri 2014-07-11 00:00:00 CEST 15h left Thu 2014-07-10 00:00:13 CEST 8h ago logrotate.timer\r\nNote\r\nTo list all timers (including inactive), use systemctl list-timers --all .\r\nThe status of a service started by a timer will likely be inactive unless it is currently being triggered.\r\nIf a timer gets out of sync, it may help to delete its stamp-* file in /var/lib/systemd/timers (or\r\n~/.local/share/systemd/ in case of user timers). These are zero length files which mark the last time\r\neach timer was run. If deleted, they will be reconstructed on the next start of their timer.\r\nExamples\r\nA service unit file can be scheduled with a timer out-of-the-box. The following examples schedule foo.service\r\nto be run with a corresponding timer called foo.timer .\r\nMonotonic timer\r\nA timer which will start 15 minutes after boot and again every week while the system is running.\r\n/etc/systemd/system/foo.timer\r\n[Unit]\r\nDescription=Run foo weekly and on boot\r\n[Timer]\r\nOnBootSec=15min\r\nOnUnitActiveSec=1w\r\n[Install]\r\nWantedBy=timers.target\r\nRealtime timer\r\nA timer which starts once a week (at 12:00am on Monday). When activated, it triggers the service immediately if\r\nit missed the last start time (option Persistent=true ), for example due to the system being powered off:\r\n/etc/systemd/system/foo.timer\r\n[Unit]\r\nDescription=Run foo weekly\r\n[Timer]\r\nOnCalendar=weekly\r\nPersistent=true\r\nhttps://wiki.archlinux.org/index.php/Systemd/Timers\r\nPage 2 of 7\n\n[Install]\r\nWantedBy=timers.target\r\nWhen more specific dates and times are required, OnCalendar events uses the following format:\r\nDayOfWeek Year-Month-Day Hour:Minute:Second\r\nAn asterisk may be used to specify any value and commas may be used to list possible values. Two values\r\nseparated by .. indicate a contiguous range.\r\nIn the below example the service is run the first four days of each month at 12:00 PM, but only if that day is a\r\nMonday or a Tuesday.\r\nOnCalendar=Mon,Tue *-*-01..04 12:00:00\r\nTo run a service on the first Saturday of every month, use:\r\nOnCalendar=Sat *-*-1..7 18:00:00\r\nWhen using the DayOfWeek part, at least one weekday has to be specified. If you want something to run every\r\nday at 4am, use:\r\nOnCalendar=*-*-* 4:00:00\r\nTo run a service at different times, OnCalendar may be specified more than once. In the example below, the\r\nservice runs at 22:30 on weekdays and at 20:00 on weekends.\r\nOnCalendar=Mon..Fri 22:30\r\nOnCalendar=Sat,Sun 20:00\r\nYou can also specify a timezone at the end of the directive (use timedatectl list-timezones to list accepted\r\nvalues)\r\nOnCalendar=*-*-* 02:00:00 Europe/Paris\r\nMore information is available in systemd.time(7).\r\nTip\r\nOnCalendar time specifications can be tested in order to verify their validity and to calculate the next time\r\nthe condition would elapse when used on a timer unit file with the calendar option of the systemd-https://wiki.archlinux.org/index.php/Systemd/Timers\r\nPage 3 of 7\n\nanalyze utility. For example, one can use systemd-analyze calendar weekly or systemd-analyze\r\ncalendar \"Mon,Tue *-*-01..04 12:00:00\" . Add --iterations=N to ask for more iterations to be printed.\r\nThe faketime command is especially useful to test various scenarios with the above command; it comes\r\nwith the libfaketime package.\r\nSpecial event expressions like daily and weekly refer to specific start times and thus any timers sharing\r\nsuch calendar events will start simultaneously. Timers sharing start events can cause poor system\r\nperformance if the timers' services compete for system resources. The RandomizedDelaySec option in the\r\n[Timer] section avoids this problem by randomly staggering the start time of each timer. See\r\nsystemd.timer(5).\r\nAdd the option AccuracySec=1us to the [Timer] section, to avoid the inaccuracy of the 1m default value\r\nof AccuracySec . Also see systemd.timer(5).\r\nSome options ( WakeSystem ) may require specific system capabilities and prevent a timer from starting,\r\nresulting in the following error messages: \"Failed to enter waiting state: Operation not supported\" and\r\n\"Failed with result 'resources'.\".\r\nTransient timer units\r\nOne can use systemd-run to create transient .timer units. That is, one can set a command to run at a specified\r\ntime without having a service file. For example the following command touches a file after 30 seconds:\r\n# systemd-run --on-active=30 /bin/touch /tmp/foo\r\nOne can also specify a pre-existing service file that does not have a timer file. For example, the following starts\r\nthe systemd unit named someunit.service after 12.5 hours have elapsed:\r\n# systemd-run --on-active=\"12h 30m\" --unit someunit.service\r\nSee systemd-run(1) for more information and examples.\r\nAs a cron replacement\r\nAlthough cron is arguably the most well-known job scheduler, systemd timers can be an alternative.\r\nBenefits\r\nThe main benefits of using timers come from each job having its own systemd service. Some of these benefits are:\r\nJobs can be easily started independently of their timers. This simplifies debugging.\r\nEach job can be configured to run in a specific environment (see systemd.exec(5)).\r\nJobs can be attached to cgroups.\r\nJobs can be set up to depend on other systemd units.\r\nJobs are logged in the systemd journal for easy debugging.\r\nCaveats\r\nhttps://wiki.archlinux.org/index.php/Systemd/Timers\r\nPage 4 of 7\n\nSome things that are easy to do with cron are difficult to do with timer units alone:\r\nCreation: to set up a timed job with systemd you need to create two files and run systemctl commands,\r\ncompared to adding a single line to a crontab.\r\nEmails: there is no built-in equivalent to cron's MAILTO for sending emails on job failure. See\r\nsystemd#Notifying with e-mail for an example of setting up a similar functionality using OnFailure= .\r\nAlso note that user timer units will only run during an active user login session by default. However, lingering can\r\nenable services to run at boot even when the user has no active login session.\r\nUsing a crontab\r\nSeveral of the caveats can be worked around by installing a package that parses a traditional crontab to configure\r\nthe timers. systemd-cron-next-gitAUR and systemd-cronAUR are two such packages. These can provide the missing\r\nMAILTO feature.\r\nAlso, like with crontabs, a unified view of all scheduled jobs can be obtained with systemctl . See\r\n#Management.\r\nManually\r\nOutside of migrating from an existing crontab, using the same periodicity as cron can be desired. To avoid the\r\ntedious task of creating a timer for each service to start periodically, use a template unit, for example:\r\n/etc/systemd/system/monthly@.timer\r\n[Unit]\r\nDescription=Monthly Timer for %i service\r\n[Timer]\r\nOnCalendar=*-*-1 02:00:00\r\nAccuracySec=6h\r\nRandomizedDelaySec=1h\r\nPersistent=true\r\nUnit=%i.service\r\n[Install]\r\nWantedBy=default.target\r\nNote See systemd.timer(5) § OPTIONS for the importance of using RandomizedDelaySec and not only\r\nAccuracySec to avoid all units started by the timer firing at once.\r\nThen one only needs to enable/start monthly@unit_name.timer .\r\nhttps://wiki.archlinux.org/index.php/Systemd/Timers\r\nPage 5 of 7\n\nTip The template units can be nested, e.g. one could enable/start monthly@btrfs-scrub@mnt-$(systemd-escape\r\nbbb76c63-e4ac-4e39-8897-a120c5d30686).timer .\r\nTips and tricks\r\nHandling \"time to live\"\r\nSome software will track the time elapsed since they last ran, for example blocking the update of a database if the\r\nlast download ended less than 24 hours ago.\r\nBy default, timers do not track when the task they launched has ended. To work around this, we can use\r\nOnUnitInactiveSeconds :\r\n/etc/systemd/system/daily-inactive@.timer\r\n[Unit]\r\nDescription=Launch %i service 24hours after it deactivated\r\n[Timer]\r\nOnUnitInactiveSec=1day1sec\r\nUnit=%i.service\r\nPersistent=true\r\n[Install]\r\nWantedBy=default.target\r\nTip With Restart=on-failure along with RestartSec , it is possible to have a unit rerun after failure and\r\nsuccess according to different schedules, see systemd.service(5) § OPTIONS.\r\nDesktop notifications\r\nThe systemd-timer-notifyAUR provides an automatic desktop notification that helps you notice when a systemd\r\nservice is triggered by a timer and is running. The notification will automatically close when the service finishes.\r\nThis can be helpful for understanding why CPU usage is high or for preventing a shutdown when a backup service\r\nhasn't finished.\r\nFor more details and configuration options, visit https://gitlab.com/Zesko/systemd-timer-notify\r\nSee also\r\nsystemd.timer(5)\r\nFedora:Features/SystemdCalendarTimers\r\nGentoo:Systemd#Timer services\r\nhttps://wiki.archlinux.org/index.php/Systemd/Timers\r\nPage 6 of 7\n\nsystemd-cron — provides systemd units to run cron scripts; using systemd-crontab-generator to convert\r\ncrontabs\r\nhttps://github.com/systemd-cron/systemd-cron || systemd-cronAUR\r\nsystemd-cron-next — tool to generate timers/services from crontab and anacrontab files\r\nhttps://github.com/systemd-cron/systemd-cron-next || systemd-cron-next-gitAUR\r\nSystemd Timers for Scheduling Tasks\r\nSource: https://wiki.archlinux.org/index.php/Systemd/Timers\r\nhttps://wiki.archlinux.org/index.php/Systemd/Timers\r\nPage 7 of 7",
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