otter-timer counts down a duration and pings the desktop through otter-osd when available. It always prints timer done on completion. Set a custom notification message or run a shell command when the timer ends.
Usage
Durations use s (seconds), m (minutes), h (hours), and d (days). Chain segments in any order:
Configuration
otter-timer reads ~/.config/otter-shell/otter-timer.conf:
default_duration: duration when none is provided on the command line
message: notification message when the timer finishes
command: shell command to run after completion
notify: set to false to suppress the desktop notification
Set default_duration to your usual timer length, like 25m for Pomodoro, so you can run otter-timer with no arguments.