I would like to replace multiple underscores with hyphens but I have 26,000 files to rename. They are all in one file structure and multiple sub-directories.

It would be much simpler if I had a script to do it. Here are some samples of the file names:

Example 1
books/horrors/small/books_horrors_small_0000000386.jpg

Rename to

books/horrors/small/books-horrors-small-0000000386.jpg

Example 2
books/comedy/small/books_comedy_small_0000001687.jpg

Rename to

books/comedy/small/books-comedy-small-0000001687.jpg

There are 26,000 files that look similer to that and are all in different directories.

The only thing I need to do is replace all the underscores _ with hyphens -