[CentOS] question

Fri Oct 17 14:52:15 UTC 2008
Jerry Geis <geisj at pagestation.com>

I am trying to increment a filename in a script example name is 000001.txt
and I need to keep the leading 0's. I have no problem if the name was 
1.txt, 2.txt etc...
var=`expr $var + 1`

however how do I keep the leading 0's?

Thanks,

Jerry