Even thought there might not be any users logged into the system, no connection the outside world, and no one at the console, there are ALWAYS processes running in Linux, even if it is only the kernel and the init daemon

• Even thought there might not be any users logged into the system, no connection the outside world, and no one at the console, there are ALWAYS processes running in Linux, even if it is only the kernel and the init daemon

• A Linux process consists of:

• a single running program
• a unique process identification number (PID)
• an environment in which to run (current shell environment or sub-shell)

• Linux keeps track of processes using the PID, as well as the relationship between them (child / parent), not by the command names or user who started it, although it tracks that info as well