Should be a simple and easy to use command-line timer.
```
climer 10M
climer 10M20S
climer 20S 10M
climer 10:20
climer 10.20
climer 20:10 -f %S.%M
climer "20 10" -f %S\s*%M
climer 10:20 -c "notify-send 'Time\'s Up!'"
climer 10:20 -o "<%M-%S-%N>"
climer 10s -q
```