Display a continually-updating countdown to a specified time.
Usage: tk-countdown [options] WHEN...
WHEN can be specified multiple times in any form accepted by date(1)
Examples: '5am tomorrow' '5 hours' (i.e., from now)
Options: --action (-a) command What to do when the time expires. The command is eval'ed as a Tcl expression. Examples: --action 'exit 1' Default: --action bell