watch command allows you to periodically run a command (default, every 2 seconds but can be specified using
--interval option). It’s like an alias for a
while 1; sleep loop and is really simple to use.
watch [options] command command_options
When I had used it, I was wanting to see the progress of the ‘dd’ command. Follow this link if you’re interested as well: http://www.commandlinefu.com/commands/view/1868/watch-the-progress-of-dd