I am looking to search and replace a character in a xml file but would like the replace part to refence a txt file with a list of characters making multiple files. so A replaced 5, B replaces 5, and C replaces 5, etc)

The text file is Filename.txt
in it is a list of characters, perhaps sometihng like this


yadda yadda...

To reference each char into the file I think something like this

for I in `cat filename.txt`
echo $I

need help