Computing/Linux/Process Control

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It is very easy to run background processes on Linux boxes without causing inconvenience to others. Every process is assigned a priority level which on Linux ranges from -20 to 20, with the default level being 0. Although it might seem a bit backward, -20 is actually the highest priority a process can have, while 20 is the lowest. To control process priority, you use the "nice" and "renice" commands. For example:

$ nice -n 20 ./mysimulation args

Otherwise, if you want to renice a process which is already running:

$ renice 20 pid

where pid is process id of the program you are running.


If you want your simulations to run even after you log out, use nohup:

$ nohup mysimulation args &

Another option is to use screen. It is a full-screen manager that multiplexes physical terminal between several processes. To start a process using screen:

$ screen mysimulation

To detach the process window and switch back to shell, type C-a d (press and hold <Ctrl>, hit <a>, release both and hit <d>). If you want to get back to your program (say to check output), then simply reattach:

$ screen -r

You can get more info from screen manual page:

$ man screen
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