systemd System and Service Manager
What is this?
systemd is a system and service manager for Linux, compatible with SysV and LSB init scripts.
systemd provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services,
offers on-demand starting of daemons, keeps track of processes using Linux control groups,
supports snapshotting and restoring of the system state, maintains mount and automount points
and implements an elaborate transactional dependency-based service control logic.
The ($) and (#) signs before all commands, just indicates how to enter the commands.
so don't actually type them. (#) means you have to be root, ($) means normal user