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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Systemd timer unit (feddit.de)

submitted 11 months ago by [email protected] to c/[email protected]

6 comments fedilink hide all child comments

I try to create a timer unit for weekly and daily backups. For example with the weekly unit, it should be executed once in a week, some minutes after login. If the unit was successful, it should shutdown and not start again until the next week. If a start of this unit was missing, it should be start again some minutes after the next login.

But for some unknown reason, the current unit starts after every login when I reboot the laptop. I am relatively sure that this timer unit is set up wrong, but unfortunately I don't know how I can implement such a unit better with the functions mentioned above.

[Unit]
Description=Run backup weekly
Requires=backup.service

[Timer]
Unit=backup.service
OnCalendar=weekly
RandomizedDelaySec=120
Persistent=true

[Install]
WantedBy=timers.target

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[–] [email protected] 10 points 11 months ago (1 children)

the timer has no idea if it was triggered during last boot. It only has the context of "this" boot, so it will do it right after a reboot and set a timer to start the service again after a week of uptime.

So if you reboot every day, it will trigger the service every day, even though you set it to weekly in the timer.

So it's up to your .service file to determine if it has been run this week or not.

[–] [email protected] 15 points 11 months ago* (last edited 11 months ago) (1 children)

the timer has no idea if it was triggered during last boot. It only has the context of "this" boot, so it will do it right after a reboot and set a timer to start the service again after a week of uptime.

This is not correct. Persistent=true saves the last time the timer was run on disk. From the systemd.timer man page:

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.

OP needs to remove Requires=backup.service from the [Unit] section so it stops running it when it start the timer on boot.

[–] [email protected] 1 points 11 months ago

This is the correct answer.