Most of the time you login into remote server via ssh. If you start a shell script or command and you exit (abort remote connection), the process / command will get killed. Sometime job or command takes a long time. If you are not sure when the job will finish, then it is better to leave job running in background. But, if you log out of the system, the job will be stopped and terminated by your shell. What do you do to keep job running in the background when process gets SIGHUP?
You may wonder – why should I shutdown the Linux box box automatically? It depends upon your situation. For example, your downloading couple of tar balls and you want to go home. You can schedule a job to shutdown Linux after downloading is completed. Linux/UNIX/BSD/OS X comes with at and cron commands to automate task. Almost all common task can be automated using at command.