Timing a script

timing.sh

#! /bin/sh

function formatSeconds() {
  local s=${1}
  ((h=s/3600))
  ((m=s%3600/60))
  ((s=s%60))
  if [ "${#h}" == 1 ]; then h="0"$h; fi
  if [ "${#m}" == 1 ]; then m="0"$m; fi
  if [ "${#s}" == 1 ]; then s="0"$s; fi
  echo "$h:$m:$s"
}

START=$(awk 'BEGIN{srand();print srand()}')

# Do what you want
echo "Hello world!"

END=$(awk 'BEGIN{srand();print srand()}')

echo "Time spent: `formatSeconds $(($END - $START))`"