How to distinguish between systemd unit run manually or by timer?

Question

I want to distinguish between systemd unit run by systemd timer or invoked manually with systemctl. I.e. to check, if backup is triggered as periodical job by schedule or is done "on demand".

What I've found so far:

• there is no place for setting environment variables in timer units ?)
• environment passed to unit is the same, regardless if it is triggered by the timer or manually

Running both periodic and manual invocations through systemd seems to be more convenient than putting note in MOTD "For scheduled operations systemd timers are used, for manual jobs use scripts in /usr/local/bin" ;)

Do you have any ideas (other than unit instantiation and copying unit with different environment for manual use )?

Answer 1

but here is a simple way to pass argument from your timer to your unit, and that is use templates

example

create a service with @ i the name

/etc/systemd/system/[email protected]

 [Unit] Description=test [Service] ExecStart=/bin/echo 'hello from %i' 

then your timer can be something like

/etc/systemd/system/me.timer

[Unit] Description=timer for me [Timer] OnUnitActiveSec=10s OnBootSec=10s [email protected] [Install] WantedBy=multi-user.target 

you see that now whatever you pass after the @ will become %i in your service file. so now you just

[~] sudo systemctl daemon-reload [~] sudo systemctl start me.timer [~] sudo systemctl status [email protected] ● [email protected] - test Loaded: loaded (/etc/systemd/system/[email protected]; static; vendor preset: enabled) Active: active (running) since Thu 2018-02-08 19:35:38 PST; 7ms ago Main PID: 8899 (echo) Tasks: 1 (limit: 4915) CGroup: /system.slice/system-me.slice/[email protected] Feb 08 19:35:38 algx systemd[1]: Started test. Feb 08 19:35:38 algx echo[8899]: hello from timer 

if you want to start the unit from the cli, just give it another param after the @

[~] sudo systemctl start me@cli [~] sudo systemctl status [email protected] ✘  ~  sudo systemctl status [email protected] ● [email protected] - test Loaded: loaded (/etc/systemd/system/[email protected]; static; vendor preset: enabled) Active: inactive (dead) Feb 08 19:32:48 algx systemd[1]: Started test. Feb 08 19:32:48 algx echo[8490]: hello from cli 

this way you have a clear distinction on what is timer and what is cli, but you can expand this to any type of trigger... you dont maintain 2 units files, but you have a clear separation because from the point of view of systemd this are 2 different services.