move files that match file names in another directory

I have two directories: dir_1 which has a.mp4, b.mp4, c.mp4, d.mp4 and dir_2 which has only a.txt, b.txt. The script should move a.mp4 and b.mp4 to dir_3 because only these file names match the file names in dir_2. I find it to hard follow the scripts when I need to do these type of particular operations.

Try,

for f in "dir_2"/*; do
    filename=${f##*/}
    mv -t "dir_3" "dir_1/${filename%.*}".*
done

• Loop files in dir_2 (use *.txt to only loop these files)
• ${f##*/} gives you the file name without the path.
• ${filename%.*} gives you the filename without extension.
• mv -t "dir_3" "dir_1/${filename%.*}".* moves all files with given filename (cleared from the extension) to dir_3. You can specify .mp4 instead of .* if you want.