So you want to change some text in many unix files.
Try the following.
perl -pi -e ’s/find/replace/g’ *.txt
or to script it out.
Find the TEXT in regular files and replace with NEWTEXT
for file in `find ./ -type f -exec grep -l TEXT {} \;`
do
perl -pi -e ’s/TEXT/NEWTEXT/g’ $file
done