Vlastna Systemd sluzba a casovac

Example: systemd Service File

[Unit]
Description=My Custom App
After=network.target
Requires=network.target

[Service]
Type=simple
ExecStart=/usr/bin/myapp --flag1 --flag2
WorkingDirectory=/opt/myapp
User=www-data
Group=www-data
Environment="ENV_VAR=value"
EnvironmentFile=/etc/myapp.env

Restart=on-failure
RestartSec=5s
TimeoutStartSec=30
TimeoutStopSec=10

StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target

systemd Type Options

• simple – Default. Runs ExecStart directly.
• forking – For daemons that fork (e.g., Apache, MySQL).
• oneshot – For scripts that run and exit (used with timers).
• notify – App notifies systemd when ready.
• idle – Runs when the system is idle.

Example: systemd Timer

mytask.service

[Unit]
Description=Run my scheduled task

[Service]
Type=oneshot
ExecStart=/usr/local/bin/my-script.sh

mytask.timer

[Unit]
Description=Run mytask.service every 15 minutes

[Timer]
OnBootSec=5min
OnUnitActiveSec=15min
Unit=mytask.service

[Install]
WantedBy=timers.target

Environment File Example

/etc/myapp.env

DB_HOST=localhost
DB_PORT=3306

Useful Commands

systemctl enable --now mytask.timer
systemctl list-timers
journalctl -u myapp.service
systemctl daemon-reload