Omitting extension with find?

Question

I need to create thumbnails from multiple .png files and would like to do this using ImageMagicks convert utility. To recursively find all files that are not thumbnails themselves, I am using the following call (split into two lines to make it readable):

find . -type f -name "*.png" -not -name "*thumb.png*" \
  -exec convert {} -thumbnail 200x200 {}.thumb.png \;`

But this would of course create a file named a.png.thumb.png when running it on a file called a.png. How could I remove the .png extension from the second {} parameter passed to convert?

Answer 1

The easiest way to do this is to pass the {} off to a shell like sh and have the shell do it:

find ... \
    -exec sh -c 'convert "$1" -thumbnail 200x200 "${1%.png}.thumb.png"' convert {} \;