watch
watch
watch [options] command [cmd_options]
Run the specified command repeatedly (by default, every two seconds) and display the output so you can watch it change over time. The command and any options are passed to sh -c, so you may need to use quotes to get correct results.
Options
Highlight changes between iterations. If cumulative is specified, the highlighting remains on the screen throughout, giving a cumulative picture of the changes.
Display help message and exit.
Run the command every secs seconds.
Do not display the header or the blank line following the header.
Print version information and exit.