#!/bin/bash

TIME_LIMIT=10
INTERVAL=1

echo
echo "Hit Control-C to exit before $TIME_LIMIT seconds."
echo

while [ "$SECONDS" -le "$TIME_LIMIT" ]
do   #   $SECONDS is an internal shell variable.
  if [ "$SECONDS" -eq 1 ]
  then
    units=second
  else  
    units=seconds
  fi

  echo "This script has been running $SECONDS $units."
  #  On a slow or overburdened machine, the script may skip a count
  #+ every once in a while.
  sleep $INTERVAL
done

echo -e "\a"  # Beep!

exit 0