Services, jobs & processes

On Ubuntu, systemd manages most system services. systemctl changes service state and configuration.

systemctl status nginxsudo systemctl start nginxsudo systemctl stop nginxsudo systemctl restart nginxsudo systemctl reload nginxsudo systemctl enable nginxsudo systemctl disable nginxsudo systemctl enable --now nginx

start and stop affect the current running state. enable configures a service to start automatically at boot but does not necessarily start it now. enable --now does both. reload asks a service to reload configuration without a full restart, where supported.

Inspect processes with:

ps auxps -eftoppgrep nginxpgrep -a nginxkill 1234kill -TERM 1234kill -KILL 1234pkill nginx

kill sends a signal to a PID. The default is SIGTERM, which asks the process to terminate cleanly. SIGKILL cannot be handled or ignored and stops the process immediately, so use it only when normal termination fails.

Shell jobs are processes started from your current shell:

long-command &jobsfg %1bg %1Ctrl+Z

& starts a command in the background. Ctrl+Z suspends the foreground job. bg resumes it in the background and fg brings it back to the foreground.

Use journalctl -u service to read a systemd service's journal. journalctl -u service -f follows new log entries live.