Bash script that counts down to the end of a workday. Helps you to survive yet another day in the office

gohome.sh

#!/bin/bash
interval=0
dif=0
cur=0

function show_time () {
    num=$1
    min=0
    hour=0
    if((num>59));then
        ((sec=num%60))
        ((num=num/60))
        if((num>59));then
            ((min=num%60))
            ((num=num/60))
            if((num>23));then
                ((hour=num%24))
            else
                ((hour=num))
            fi
        else
            ((min=num))
        fi
    else
        ((sec=num))
    fi
    prog=$((cur - start))
    tot=$((end - start))
    echo -ne "\rYou can go home in: $hour"h "$min"m "$sec"s " | ("$(bc <<< "scale=3; $prog*100/$tot") "%)"
}


while true ; do
	#get current time
	hour=$(date +%H)
	min=$(date +%M)
	sec=$(date +%S)
	#calculate current time in seconds
	cur=0
	((cur += 10#$hour * 3600))
	((cur += 10#$min * 60))
	((cur += 10#$sec))

	#calculate difference
	dif=$(($end - $cur))

	#show time left
	show_time $dif

	#parse difference in seconds to readable format

	#wait for specified interval time (seconds)
	sleep $interval
done