Ubuntu Unleashed 2013 Edition: Covering 12.10 and 13.04, Eighth Edition

Using the kill Command to Control Processes

The kill command is a basic UNIX system command. You can communicate with a running process by entering a command into its interface, such as when you type into a text editor. But some processes (usually system processes rather than application processes) run without such an interface, and you need a way to communicate with them as well, so you use a system of signals. The kill system accomplishes that by sending a signal to a process, and you can use it to communicate with any process. The general format of the kill command is as follows:

matthew@seymour:~$ kill option PID

Note that if you are using kill on a process you do not own, you need to have super user privileges and preface the kill command ...