watch [options] command

-b, --beep             beep if command has a non-zero exit
-c, --color            interpret ANSI color and style sequences
-d, --differences[=<permanent>]
                       highlight changes between updates
-e, --errexit          exit if command has a non-zero exit
-g, --chgexit          exit when output from command changes
-n, --interval <secs>  seconds to wait between updates
-p, --precise          attempt run command in precise intervals
-t, --no-title         turn off header
-x, --exec             pass command to exec instead of "sh -c"

-h, --help     display this help and exit
-v, --version  output version information and exit

watch -n 5 date

watch -t <command>

watch -d <command>