do while example with sh

#!/bin/sh
# do while example with sh, and It is the infinite loop.
# tips from man sh.

# = Main =
#f="0"
#while : f
#do
#   f=$(($f + 1))    # like java`s "f = f + 1;"
#
#   if [ $f -lt 10 ]; then
#       echo "0$f"
#   else
#       echo "$f"
#   fi
#   sleep 3
#done

padtowidth=2

while : f
do
    f=$(($f + 1))    # like java`s "f = f + 1;"
    printf "%0*d\n" $padtowidth $f;
    sleep 3
done


# = Result =
01
02    # inter 3s.
03
...

# = Reference =
# * In bash, how could I add integers with leading zeroes and maintain a specified buffer - Stack Overflow http://stackoverflow.com/questions/3191067/in-bash-how-could-i-add-integers-with-leading-zeroes-and-maintain-a-specified-b