background jobs are very much useful to run the jobs with low priority in the background and high priority jobs in the foreground and we can do our regular quickly and remaining work later. we can add much more number of background jobs depending upon the performance of the system and load permit and work. there are two types of mechanisms are there for doing background jobs. 1. & and 2. nohup command. see Unix concepts and Applications, sumithabha das,topic No.9, process for more information you can download ebook freely and see that from 5GB of free space to upload and share your files, photos, videos and music - eSnips.com