Preserving whitespace in here document.

I'm trying to write a script that will preserve the white space in a here document. What I'm trying to do is write a "smart" sed script. I have a text file that needs to update a number sequentially.

For example
..indx=1
....indx=2
......indx=3

I want to insert an indx at line 2:
..indx=1
....indx=#
....indx=2
......indx=3

and have the outcome be the following
..indx=1
....indx=2
....indx=3
......indx=4

Getting the numbers is easy and making the replacements is easy, but if I use a while read loop none of the white space is preserved.

while read line
do
* do stuff *
echo "$line"
done < ~/tmp/myfile

this would return

indx=1
indx=2
indx=3
indx=4

thanks for any help

Was looking at my unix in a nutshell book table of contents. Just for kicks I went to the Shell Programming section. I saw a built-in command called line. which reads in a line of input from stdin and outputs it to stdout.

while line=`line`
do
echo line="$line"
done < ~/tmp/testfile.txt

This preserved the whitespace.