watch

Execute a program periodically and display its output.

Warning

Shell aliases are difficult to use with watch, steer clear.

Simple command:

$ watch wc -l foo/\*

Use bash in command:

$ watch -x bash -cl "find foo/ -exec wc -l {} \;"

Options

-d, --differences

Highlight the differences between successive updates. Option will read optional argument that changes highlight to be permanent, allowing to see what has changed at least once since first iteration.

-g, --chgexit

Exit when the output of command changes.

-n, --interval seconds

Specify update interval. The command will not allow quicker than 0.1 second interval, in which the smaller values are converted. Both . and , work for any locales. The WATCH_INTERVAL environment can be used to persistently set a non-default interval (following the same rules and formatting).

-x, --exec

Pass command to exec instead of sh -c which reduces the need to use extra quoting to get the desired effect.