Hello,

I have been trying to create a system service that would run a script on shutdown (hence why I went for a system service over a user service) and landed on something like this

[Unit]
Description=Run backup script on shutdown
DefaultDependencies=no
Before=poweroff.target halt.target
Requires=network.target

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/bin/true
ExecStop=/var/home/blackeco/scripts/backup.sh
User=blackeco
Group=blackeco

[Install]
WantedBy=poweroff.target halt.target

Unfortunately, when the shutdown occurs, systemd fails to execute the script:

backup-on-shutdown.service: Unable to locate executable '/var/home/blackeco/scripts/backup.sh': Permission denied
backup-on-shutdown.service: Failed at step EXEC spawning /var/home/blackeco/scripts/backup.sh: Permission denied

This script is correctly owned by user blackeco and permissions look fine

$ ls -la /var/home/blackeco/scripts
drwxr-xr-x. 1 blackeco blackeco 154  5 Feb. 13:50 ./
drwxr-xr-x. 1 blackeco blackeco 116  3 Feb. 13:07 ../
-rwxr-xr-x. 1 blackeco blackeco 794  4 Feb. 15:44 backup.sh*

I’m very puzzled as to why. I’m running Bluefin 41 (itself based on Fedora Silverblue 41).

  • BlackEcoOP
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    2 days ago

    From what I gathered from the comments, system services cannot access the home directory by design: user services should be used instead.

    But since it is nearly impossible to execute a user service on shutdown, I changed my approach and went for a user service and a timer that initiates a backup every 15 minutes. Since the backups are incremental, it shouldn’t take too much time nor space.

    • @[email protected]
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      2 days ago

      How long does it take to run? Can you run it on login and then execute what you need when you receive the sigkill signal?

  • Björn Tantau
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    22 days ago

    Can you put the script somewhere else in var? /usr/local or /opt are usually for distro-external stuff.

    • BlackEcoOP
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      2 days ago

      I could, but I need the script to access my home in order to do the backup, and from what I gathered from Leaflet system services can’t access it.

  • Björn Tantau
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    22 days ago

    I’m not familiar with Silverblue but home being in /var is sus. Usually it’s in /home. But maybe it’s mounted in a weird Silverblue way and gets unmounted before it runs.

    But running scripts on shutdown is hard to impossible. I always wanted to run automatic updates on shutdown but they don’t have networking even if the unit file requires networking. I haven’t seen anyone properly manage to do that yet, so good luck. And please make a post if it does end up working. Then I will revisit my own efforts again.

    • @[email protected]
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      42 days ago

      It’s not sus at all. The reason /home is in /var is because /var and /etc are the only writeable directories on the system. There is a /home, but it’s actually just a symlink to /var/home.

      This is how all of the Fedora atomic systems are set up, and it’s been the case for a lot of the other immutable distros I’ve tried. It’s just a different way of doing things.

    • @[email protected]
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      22 days ago

      If that’s the reason maybe OP can add the shutdown as the last step on the script and execute the script instead of the shut down button as a work around.

      • BlackEcoOP
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        12 days ago

        No, I really don’t want to hijack the UI for this, as it could break with a DE update. And that wouldn’t work when shutting down from the console.

        • @[email protected]
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          2 days ago

          Doesn’t have to be, e.g. I have a stream deck and mapped a script to one of the buttons. Or put it as an executable file on your desktop or wherever and use it instead of the normal shutdown button.

    • BlackEcoOP
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      22 days ago

      I haven’t seen anyone properly manage to do that yet, so good luck.

      Yes, that’s the whole problem, Internet is littered with posts on running a script on shutdown but none of my attempts so far has been successful.

  • Leaflet
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    22 days ago

    Is this a systemd user service?

      • Leaflet
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        42 days ago

        This seems to be a systemd feature, system services can’t touch home directories by default.

        https://unix.stackexchange.com/a/684074

        I think a user script would still work. Or you could set the flag that would let system services access your home.

        • BlackEcoOP
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          32 days ago

          I would try ProtectHome=read-only but then restic wouldn’t be able to write its local cache to ~/.restic.

          I went for a user service first to make my life easier, but unfortunately you can’t use targets poweroff.target and halt.target

          Unit /etc/systemd/user/backup-on-shutdown.service is added as a dependency to a non-existent unit poweroff.target
          Unit /etc/systemd/user/backup-on-shutdown.service is added as a dependency to a non-existent unit halt.target.
          

          I may be in a bind then…

  • @[email protected]
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    12 days ago

    This might be a weird thing with how the environment variables get passed around. I’ll see if I can find my own service I wrote, but I remember having to do something with env in the ExecStart part to get my daemon to run.

    Maybe you’ll find a clue about that in the meantime!

  • Kerb
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    2 days ago

    is your home folder actually under /var/home/… not under /home/… ?

    does the scripr run correctly when you paste the full path in the comandline?

    • Leaflet
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      42 days ago

      Fedora Atomic, and by extension Universal Blue, does put the home in /var. It’s to denote that the directory is mutable.

    • BlackEcoOP
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      42 days ago

      is your home folder actually under /var/home/… not under /home/… ?

      Yep, it’s how Silverblue is set up

      $ ls -l /home
      lrwxrwxrwx. 4 root root 8 28 janv. 13:51 /home -> var/home/
      

      does the scripr run correctly when you paste the full path in the comandline?

      Yes

  • @[email protected]
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    2 days ago

    What are the permissions all the way to the script ? Can blackeco reach the script ?

    • BlackEcoOP
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      12 days ago
      drwxr-xr-x. 1 root root   26 28 Jan. 13:03 /var
      drwxr-xr-x. 1 root root  228  3 Feb. 09:55 /var/home
      drwx------. 1 blackeco blackeco 1544  5 Feb. 17:52 /var/home/blackeco
      drwxr-xr-x. 1 blackeco blackeco 116  3 Feb. 13:07 /var/home/blackeco/scripts
      -rwxr-xr-x. 1 blackeco blackeco 794  4 Feb. 15:44 /var/home/blackeco/scripts/backup.sh*
      

      And yes, blackeco can reach it