I understand now.
what your doing is
sed -e 's/D/walter/g' CD*
which replaces the D with Walter in each file. The ouput is going to the screen to so the files themselves are unaffected.
You need to redirect the output to a new file name.
The bit of code that I put up before, in your last message should do the trick.
https://www.unix.com/showthread.php?s...4194#post24194