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c/linuxquestions · by BlackEco@lemmy.blackeco.com · 1y

Execute script located in $HOME from system systemd service

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).

10 points · 18 comments · view on lemmy.world

18 Comments

BlackEco@lemmy.blackeco.com · 5 pts · 1y (1 reply)

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.

ryannathans@aussie.zone · 1 pts · 1y

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?

that_leaflet@lemmy.world · 2 pts · 1y (3 replies)
[ removed ]
BlackEco@lemmy.blackeco.com · 2 pts · 1y (2 replies)

As I said, this is a system service

that_leaflet@lemmy.world · 4 pts · 1y (1 reply)
[ removed ]
BlackEco@lemmy.blackeco.com · 3 pts · 1y

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...

bjoern_tantau@swg-empire.de · 2 pts · 1y (1 reply)

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

BlackEco@lemmy.blackeco.com · 1 pts · 1y

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.

bjoern_tantau@swg-empire.de · 2 pts · 1y (5 replies)

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.

Telorand@reddthat.com · 4 pts · 1y

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.

whatsgoingdom@rollenspiel.forum · 2 pts · 1y (2 replies)

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.

BlackEco@lemmy.blackeco.com · 1 pts · 1y (1 reply)

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.

whatsgoingdom@rollenspiel.forum · 1 pts · 1y

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.

BlackEco@lemmy.blackeco.com · 2 pts · 1y

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.

Kerb@discuss.tchncs.de · 1 pts · 1y (2 replies)

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?

that_leaflet@lemmy.world · 4 pts · 1y
[ removed ]
BlackEco@lemmy.blackeco.com · 4 pts · 1y

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

Telorand@reddthat.com · 1 pts · 1y

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!

BestBouclettes@jlai.lu · 1 pts · 1y (2 replies)

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

BlackEco@lemmy.blackeco.com · 1 pts · 1y (1 reply)
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

BestBouclettes@jlai.lu · 1 pts · 1y

Can you manually run the script ?