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pid

What are PIDs used for?

I know how to get a PID of a running process in Ubuntu, but aside from killing a running process, what else can the PID be used for?

Solution

  • The question is a bit broad. Maybe it helps to explain what a PID is:

    Meaning of PID

    PID = Process ID = Process Identifier

    Every process on your system is assigned an unique number. This number is the PID. The PID is only there so that you can specify a process unambiguously. So the question should rather be:

    What operations can be done on processes.

    Operations on Processes

    • Sending signals (with kill). Signals can be used for more than just killing programs, for instance dd can output its current progress when sending the USR1 signal.

    • Changing priority (with renice). Processes have a priority which determines how much CPU time they get compared to other processes. The priority can be changed by you.