Deleting all files that do not match a certain pattern - Windows command line

I would do it like this:

attrib +r *.jpg
del /q *
attrib -r *.jpg

This will first make all JPG files read-only, delete everything else (it will automatically skip read-only files), and then make the JPG files writeable again.

That's actually pretty easy.

You'll need for to iterate over the files and then simply look for the extension:

for %f in (*) do if not %~xf==.jpg del "%f"

should do the trick (code here).

I know it's not answering your question directly, but have you looked at the options on your converter to see if:

1. It can delete the originals itself

or

2. Write the .jpg's to a new folder?

I was looking for a way to find all files that did NOT have the extension ".mp3" in a directory TREE on Windows 7 (NTFS volume) containing perhaps 20,000 files in several hundred directories of various depths... so after a bit of angst, I used:

cd <theplace>
dir /S | find /V "<DIR>" | find /V "Total" | find /V "bytes" | find /V "Directory" | find /V "Volume" | find /V ".mp3" | more /S

this listed the files that did not match the .mp3 after stripping out everything related to the DIR command output... 99% works... unless the file that doesn't match is named one of the keywords in the standard DIR output - perhaps there's a way to make DIR report less header/summary info - but I didn't bother as this got most of the way there.