Definition: Unlike with a foreground process, the shell does not have to wait for a background process to end before it can run more processes. (More below.)Within the limit of the amount of memory available, you can enter many background commands one after another. To run a command as a background process, type the command and add a space and an ampersand to the end of the command. For example:
$ command1 &
Immediately after entering the above command, the shell will execute the command. While that is running in the background, the shell prompt (% for the C Shell, and $ for the Bourne Shell and the Korn Shell) will return. At this point, you can enter another command for either foreground or background process. Background jobs are run at a lower priority to the foreground jobs.
You will see a message on the screen when a background process is finished running.
Also Known As: Background Command.