Rename multiple files based on pattern in Unix

Question

There are multiple files in a directory that begin with prefix fgh, for example:

fghfilea
fghfileb
fghfilec

I want to rename a

Answer 1

I wrote this script to search for all .mkv files recursively renaming found files to .avi. You can customize it to your neeeds. I've added some other things such as getting file directory, extension, file name from a file path just incase you need to refer to something in the future.

find . -type f -name "*.mkv" | while read fp; do 
fd=$(dirname "${fp}");
fn=$(basename "${fp}");
ext="${fn##*.}";
f="${fn%.*}";
new_fp="${fd}/${f}.avi"
mv -v "$fp" "$new_fp" 
done;