Run a program at boot as a systemd service

The smallest useful systemd service: run one program at boot, restart it if it dies, and manage it with systemctl. This is the base every other service recipe builds on.

The unit

Save as /etc/systemd/system/myapp.service:

[Unit]
Description=My application
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
ExecStart=/usr/local/bin/myapp --port 8080
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

• Type=simple (the default) means ExecStart is the main process and systemd considers the service started as soon as it forks. Use Type=exec on modern systemd for slightly stricter start semantics.
• ExecStart= must be an absolute path (no $PATH lookup). Pass arguments on the same line.
• WantedBy=multi-user.target is what makes enable hook it into boot (the normal non-graphical “system is up” target).

Enable and start

sudo systemctl daemon-reload
sudo systemctl enable --now myapp.service

enable --now does both: start it now and start it on every boot. (enable alone only sets the boot link; start alone only runs it this once.)

Check it

systemctl status myapp.service
journalctl -u myapp.service -f

Anything your program writes to stdout/stderr is captured by the journal automatically — no need to redirect to a log file.

Gotchas: if the program forks into the background itself (an old-style daemon), use Type=forking and set PIDFile=. If it talks to the network, keep After=/Wants=network-online.target so it doesn’t start before the network is up. After any edit to the file, run systemctl daemon-reload before restart.