Systemd service running bash script fails

Question

On Arch Linux, I am trying to create a systemd service which runs this Bash script:

#!/bin/bash

/bin/xbindkeys &
/bin/setxkbmap -layout gb

With some online guidance I then made a file named myfirst.service in /etc/systemd/system to store my service. Here are the contents of the file:

[Unit]
Description=Command Service

[Service]
ExecStart=/etc/startupjobscript
User=user1
Type=oneshot
Restart=on-abort
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

The service is supposed to execute /etc/startupjobscript, which is the Bash script. After this I enabled and started the service with:

systemctl enable myfirst
systemctl start myfirst

But for some reason it doesn't work and shows that it has failed to load and run at all.

EDIT: here is what sudo systemctl status myfirst give me:

Warning: The unit file, source configuration file or drop-ins of myfirst.service changed on disk. Run 'systemctl daemon-reload' to reload units.
● myfirst.service - Command Service
     Loaded: loaded (/etc/systemd/system/myfirst.service; enabled; vendor preset: disabled)
     Active: failed (Result: exit-code) since Wed 2020-08-26 21:07:02 BST; 18min ago
    Process: 332 ExecStart=/etc/startupjobscript (code=exited, status=255/EXCEPTION)
   Main PID: 332 (code=exited, status=255/EXCEPTION)

Aug 26 21:07:01 archlinux systemd[1]: Starting Command Service...
Aug 26 21:07:02 archlinux startupjobscript[337]: Cannot open display "default display"
Aug 26 21:07:02 archlinux systemd[1]: myfirst.service: Main process exited, code=exited, status=255/EXCEPTION
Aug 26 21:07:02 archlinux systemd[1]: myfirst.service: Failed with result 'exit-code'.
Aug 26 21:07:02 archlinux systemd[1]: Failed to start Command Service.

Answer 1

When running anything that talks to the X-server, systemd services get a little tricky. There are two main methods to do it:

1. Run a user service
2. Set $DISPLAY and avoid starting until graphical.target is reached.

To run this as a user-service, move myfirst.service to ~/.config/systemd/system/. Then remove User= and set WantedBy= to default.target. default.target is reached when the user logs in. Some day there will be a graphical-session.target which will be reached when a user is logged into a desktop environment, but that's not available yet. Instead we are triggering off of default.target which is reached when a user logs in. If you're using a display manager, then you probably have an x-session before then.

[Unit]
Description=Command Service
After=default.target

[Service]
ExecStart=/bin/xbindkeys
ExecStartPost=/bin/setxkbmap -layout gb
Type=simple
Restart=on-abort

[Install]
WantedBy=default.target

Be sure to use --user when working with this unit such as:

systemctl --user daemon-reload
systemctl --user start myfirst.service
systemctl --user enable myfirst.service

---

To keep this as a system service, leave the file in /etc/systemd/system/ and you'll need to set environment so it can connect to the X-server. Finally, be sure to make it WantedBy=graphical.target. This ensures it doesn't try to connect to the X-server before the X-server is started. However I'm not sure that it will always succeed because I'm not sure that the .Xauthority is valid until you log in.

[Unit]
Description=Command Service
After=graphical.target

[Service]
ExecStart=/bin/xbindkeys
ExecStartPost=/bin/setxkbmap -layout gb
Type=simple
User=user1
Environment=DISPLAY=:0
Environment=XAUTHORITY=/home/user1/.Xauthority
Restart=on-abort

[Install]
WantedBy=graphical.target

The system-wide service thing gets a little weird if you have multiple users or multiple displays. It's recommended to do the user-specific thing. If you are in your desktop environment, you can echo $DISPLAY and echo $XAUTHORITY to figure out what to set those variables to.

---

Once you make these changes, you'll need to tell systemd to read them before you try your next start. Run:

systemctl daemon-reload

If you've been experimenting, be sure to systemctl disable myfirst.service first, then when you are sure systemctl start myfirst.service works, then you can systemctl enable myfirst.service. enable will create a symbolic link in default.target or graphical.target so that when you reboot, your service gets called. To avoid making a mess with those links during your experimentation state, just don't enable it until you're ready to test reboots.

---

Note, I do have a strange suspicion about that /bin/xbindkeys & line in your bash script. Does xbindkeys normally run forever? If so, you might want to change your ExecStart= to:

ExecStart=/bin/xbindkeys
ExecStartPost=/bin/setxkbmap -layout gb
Type=simple

I've made these changes to the suggested units above already.

This will ensure that systemd keeps track of the process directly instead of forking. Because Type= is not set to forking, I suspect that the bash script will end and systemd won't keep track of the PID of xbindkeys leaving it as an orphaned PID and no way to stop it. If you leave xbindkeys as part of the ExecStart then stopping the service will terminate xbindkeys (which I think it will fail to do right now). In that case you'll also want to set Type=simple because oneshot won't be applicable anymore.