bg is a job control command which resumes suspended jobs without bringing them to the foreground.

bg [job]


In this example, let’s assume we are in the bash shell.

If you initiate a process at the command line, and you want to return to the command line prompt before the program is finished executing to do something else – check your mail, edit a text file, whatever – you can press Control-Z and the job will stop.

If you then run the command:
bg %1

The stopped job will resume operation, but remain in the background. It will not receive any input from the terminal while it’s in the background, but it will keep running, and you can continue to use the shell from the command line.