systemd

systemd is a suite of basic building blocks for a Linux system. It provides a system and service manager that runs as Process ID 1 and starts the rest of the system.

To manage the services run the following commands:

• systemctl or systemctl list-units : This command lists the running units.
• systemctl --failed : This command lists failed units.
• systemctl list-unit-files : This command lists all the installed unit files. The unit files are usually present in /usr/lib/systemd/system/ and /etc/systemd/system/.
• systemctl status pid : This command displays the cgroup slice, memory and parent for a PID.
• systemctl start unit : This command starts a unit immediately.
• systemctl stop unit : This command stops a unit.
• systemctl restart unit : This command restarts a unit.
• systemctl reload unit : This command asks a unit to reload its configuration.
• systemctl status unit : This command displays the status of a unit.
• systemctl enable unit : This command enables a unit to run on startup.
• systemctl enable --now unit : This command enables a unit to run on startup and start immediately.
• systemctl disable unit : This command disables a unit and removes it from the startup program.
• systemctl mask unit : This command masks a unit to make it impossible to start.
• systemctl unmask unit : This command unmasks a unit.

To get an overview of the system boot-up time, run the following command:

systemd-analyze

To view a list of all running units, sorted by the time they took to initialize (highest time on top), run the following command:

systemd-analyze blame