Linux rename files based on another file in the directory?

Question

I\'ve got about 750 directories that contain two files each:

long_somewhat_random_filename.jpg
thumb.jpg

What I\'d like to do is use find

Answer 1

Give the script below a shot. Right now the echo makes it benign so you can try before you buy so to speak. If you like what you see, remove the echo and run the script again to actually make the changes.

#!/bin/bash

while read file; do
 echo mv "${file%/*}/thumb.jpg" "${file%.*}_thumb.jpg"
done < <(find . -type f ! -name "thumb.jpg" -name "*.jpg")

Input

$ find . -type f -name "*.jpg"
./dir1/dir1_foo_bar.jpg
./dir1/thumb.jpg
./dir2/dir2_foo_bar.jpg
./dir2/thumb.jpg
./dir3/dir3_foo_bar.jpg
./dir3/thumb.jpg
./dir4/dir4_foo_bar.jpg
./dir4/thumb.jpg
./dir5/dir5_foo_bar.jpg
./dir5/thumb.jpg

Output

$ ./mvthumb.sh
mv ./dir1/thumb.jpg ./dir1/dir1_foo_bar_thumb.jpg
mv ./dir2/thumb.jpg ./dir2/dir2_foo_bar_thumb.jpg
mv ./dir3/thumb.jpg ./dir3/dir3_foo_bar_thumb.jpg
mv ./dir4/thumb.jpg ./dir4/dir4_foo_bar_thumb.jpg
mv ./dir5/thumb.jpg ./dir5/dir5_foo_bar_thumb.jpg