//echo -a $duration(-12345,3)
now: 00:00:-12345
new: -03:25:45
//echo -a $duration(-12345)
now: -12345secs
new: -3hrs 25mins 45secs
//echo -a $duration(-12345,2)
now: -12345secs
new: -3hrs 25mins
translating back to integer:
//echo -a $duration(-03:25:45)
now: -9255
new: -12345
//echo -a $duration(-12345secs)
now: 0
new: -12345
//echo -a $duration(-3hrs 25mins 45secs)
now: 1545
new: -12345