watch - execute a program periodically, showing output fullscreen

syntax
$ watch [option] [command]

To Run Command with a Custom Interval
$ watch -n 5 free -h
$ watch -n 3 date

To highlight changes between updates
$ watch -d [command]
$ watch -d date
$ watch -d free -h

To exit if there is a change in the output
$ watch -g [command]
$ watch -g free

To hide the watch Command Header
$ watch -t date

To alert on error
$ watch -b [command]



regards,
T.Dhanasekar