[CentOS] Shell Script Question

> What's the simplest way to increment the number 0000 up by one until some other 4 digit number while
> preserving leading zero's until the 1000's has a digit other than 0?

Lots of answers, depending on the shell.  I like this version for ksh:

  typeset -Z4 a=-1
  while (( a++ < 1000 ))
  do
    print $a
  done

Not enough use is made of typeset :-)

-- 

rgds
Stephen