The example below shows how to calculate elapsed time. This is useful if you want to measure the performance of your script.

# Start time: Get time as a UNIX timestamp (seconds elapsed since Jan 1, 1970 0:00 UTC) T="$(date +%s)" # Doing some intensive work for 2 days, 4 hours and 51 minutes. sleep 3s T=$((T-2*86400)) # Add 2 days T=$((T-4*3600)) # Add 4 hours T=$((T-51*60)) # Add 51 minutes # Get total elapsed time T="$(($(date +%s)-T))" printf "Elapsed time[DD:HH:MM:SS]: %02d:%02d:%02d:%02d \n" \ "$((T/86400))" \ "$((T/3600%24))" \ "$((T/60%60))" \ "$((T%60))"

**Output**

Elapsed time[DD:HH:MM:SS]: 02:04:51:03