UNIX for Dummies Questions & Answers

sleepVal=5

 while [ ${counter} -le 10 ]
    do
     printf "%d) %s\n" ${counter} `date +%d-%m-%Y:%R-%S` 
     sleep ${sleepVal}
     counter=`expr ${counter} + 1`
    done

$ cat exprTest
count=1000

counter=0
printf "With expr, Start: "
date
while [ $counter -le $count ]; do
  counter=`expr $counter + 1`
done
printf "With expr, End:   "
date
echo $counter

counter=0
printf "Without expr, Start: "
date
while [ $counter -le $count ]; do
  ((counter++))
done
printf "Without expr, End:   "
date
echo $counter


$ ./exprTest
With expr, Start: Mon  4 Apr 2011 22:13:59 CEST
With expr, End:   Mon  4 Apr 2011 22:14:01 CEST
1001
Without expr, Start: Mon  4 Apr 2011 22:14:01 CEST
Without expr, End:   Mon  4 Apr 2011 22:14:01 CEST
1001