BCA - UNIX and Shell Programming

Background jobs are unable to receive keyboard input or signals such as Control-C from the controlling terminal. Foreground jobs are terminated by a hang-up signal if the login session is disconnected, while background jobs are not. The controlling terminal can be written to by both foreground and background jobs.

kill -9 %1          Kill a job, by specifying its job number after the percent sign 

kill -9 123         Kill a process, by specifying its process id (PID) number

bg                    Run the most recently stopped job in the background

fg                     Bring most recently backgrounded job to the foreground