Watch
Usage: Watch [-v] [-t] [-p <path>] [-x <regexp>] <command>
Watches for changes in a directory tree, and runs a command when
something changed. By default, the output goes to an acme win.
-t sends the output to the terminal instead of acme
-v enables verbose debugging output
-p specifies the path to watch (if it is a directory then it watches recursively)
-x specifies a regexp used to exclude files and directories from the watcher.