Your own service unit and applying changes

Articles

• nologin — a shell that refuses login — A login-shell replacement that reports refusal and exits instead of opening an interactive shell.
• useradd — create a user — The useradd command creates a user account with a home directory, shell, groups and UID; passwd sets the password.
• Processes — Viewing processes, signals and priorities; finding the processes that hog CPU or memory.
• systemd — System and service manager that manages units and their dependencies.
• systemctl — managing systemd services — Command for managing systemd units and inspecting their state.