Recipe: Monitoring command outputs with watch

$ watch COMMAND
Eg:
$ watch ls
or
$ watch 'COMMANDS'
Eg:
$ watch 'ls -l | grep “^d”' 
# list only directories

$ watch -n 5 'ls -l'
#Monitor the output of ls -l at regular intervals of 5 seconds

Highlighting differences
========================
$ watch -d 'COMMANDS'