Mastering Bash

DEMO

This sends a process into the background. Look at this:

zarrelli:~$ echo "Hello, see you in 5 seconds" ; sleep 5 Hello, see you in 5 seconds

It will hold the prompt for 5 seconds only if you put sleep in the background:

zarrelli:~$ echo "Hello, see you in 5 seconds" ; sleep 5 &Hello, see you in 5 seconds[1] 8163

The shell will give you back control immediately, since the sleep process will not get any more input from the terminal, leaving the command line available to the user. One of the benefits of this is that while you are limited to a single foreground process at time. Since during its execution, you will not be able to enter any other commands with background processes, you can spawn as many as you wish, given the system resources. ...