Time condition loop in shell

Question

I have just started learning shell script recently, so I don\'t know much about it.

I am trying to find example of time based while loop but not having any luck.

Answer 1

date +%s will give you the seconds since the epoch, so something like

startTime = `date +%s`
timeSpan = #some number of seconds
endTime = timeSpan + startTime

while (( `date +%s` < endTime )) ; do
    #code
done

You might need some edits, since my bash is rusty

Answer 2

This is exactly what I was looking for, here is a one line solution based on bsravanin's answer:

end=$((SECONDS+30)); of=$((end-SECONDS)) ; while [ $SECONDS -lt $end ]; do echo $((end-SECONDS)) seconds left of $of ; sleep 1 ; done;