I dunno, sounds like a one liner in cli … unless you need to do this many times in the future or just want to force it into Emacs for fun (which is okay :), strikes me as a 10s thing to do on cli if you’rr a Mac or Unix-like user

cd /to/top mv */*mov .

Repeat for other file type.

That assumes they’re only one level deep

Another one liner …

find /top -name “*mov” -exec “mv {} /top” ;

Be careful as just tapping out on phone but you get the idea

For an elisp solution (not dired, still in Emacs):

             (rename-file filename ))
           (directory-files-recursively  "."))

You can filter via the second argument of directory-files-recursively which files you want to list (using a regexp), or use any test you want in the lambda.

Not the fastest if you have a large amount of files, as it is pure elisp.

You don’t need to move files around just to bulk rename them. If you want to do it, sure, you can, but you don’t have to.

In your top level directory:

1. C-u C-x d (alternatively C-u M-x dired)

You will be in minibuffer now. Be sure dired listing switches have -l and -R option; -l is probably already there among anything else you might use; just type space and add -R at the end and type Return (Enter)

Now you will have a Dired buffer with al the subdirectories and files in them listed in the same buffer.

2. C-x C-q in Dired to switch to WDired mode (I have bound it in my Emacs to C-S-r for easier typing)

You are now in “writeable dired” mode where you can edit all file names as if it were an ordinary text buffer. You can also use replace-string for example to replace a part of the name in all filenames at once, regex-replace, etc. You can do it manually, or whatever else you would do in a text buffer.

3. C-c C-c to save your changes when you are done; all files will be updated.

You could use M-x find-name-dired to list the files matching a pattern in the directory and subdirectories in a Dired buffer. See: https://www.gnu.org/software/emacs/manual/html_node/emacs/Dired-and-Find.html

The manual also says that you could use the recursive flag for ls, but I’ve never tried it. See: https://www.gnu.org/software/emacs/manual/html_node/emacs/Subdirectories-in-Dired.html

I can think of two options:

1. M-x find-dired RET RET RET (or adjust query): which will list all files recursively in dired. You probably don’t need to copy them elsewhere for renaming. Use M-x dired-toggle-read-only (or C-x C-q), rename in-place, and commit (toggle again C-x C-q). https://xenodium.com/batch-renaming-with-counsel-find-dired-and-wdired
2. dired-subtree: enables drilling down to multipe subdirectories from the same dired buffer. Expand the subdirectories needing management, and edit like 1. (via C-x C-q) https://xenodium.com/drill-down-emacs-dired-with-dired-subtree

Edit: markup

I know this is the emacs subreddit but I think it would be a better task for just the CLI ‘find’ command with mindepth and exec