Process control

In this article you can find useful information about handling processes in Linux/Unix systems like how to send a command in the background. Every New Systems Administrator should know how to use those commands.


ps (=print status) Display the list of currently running processes with their process IDs (PID) numbers. Use "ps axu"to see all processes currently running on your system (also those of other users or without a controlling terminal), each with the name of the owner. Use "top" to keep listing the processes currently running.
fg PID Bring a background or stopped process to the foreground.
bg PID Send the process to the background. Opposite to fg. The same can be accomplished with z.
kill PID Force a process shutdown. First determine the PID of the process to kill using ps.
anycommand& Run any command in the background (the symbol "&" means "run the proceeding command in the background")
killall programme_name Kill program(s) by name.
xkill (in an xwindow terminal) Kill a GUI-based program with mouse. (Point with your mouse cursor at the window of the process you want to kill and click.)
lpc (as root) Check and control the printer(s). Type "?" to see the list of available commands.
lpq Show the content of the printer queue. Under KDE (X-Windows), you may also use GUI-based "Printer Queue" available from "K"menu-Utilities.)
lprm job_number Remove a printing job "job_number" from the queue.
Run program_name adjusting its priority. Since the priority is not specified in this example, it will be adjusted by 10 (the process will run slower), from the default value (usually 0). The lower the number (of "niceness" to other users on the system), the higher the priority. The priority value may be in the range -20 to 19. Only root may specify negative values. Use "top" to display the priorities of the running processes.
renice -1 PID (as root) Change the priority of a running process to -1. Normal users can only adjust processes they own, and only up from the current value (make them run slower).
Posted on: 14/12/2009

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