Give all files a .jpg extension

Question

I have a directory and some of the files' extensions are in uppercase (.JPG) instead of lowercase.

I want to make sure every file has .jpg as its extension. How would I do this from a shell prompt?

Answer 1

Using Shell Parameter Expansion:

for f in *.JPG; do
    mv "${f}" "${f%%.JPG}.jpg"
done

The " characters will take care of filenames containing spaces, as photographs often do.

Answer 2

If you can use external tools (not only bash), check rename command!

rename .JPG .jpg *

The rename is part of util-linux.

Answer 3

If you do have spaces in filenames:

for f in *.JPG; do [[ -f "${f}" ]] && mv "${f}" "${f/%JPG/jpg}"; done

Answer 4

I would suggest to have a look at the mmv command. It's suited exactly for this kind of tasks. In your scenario it would be:

#> mmv "*.JPG" "#1.jpg"

The man page is full of examples, so it takes no time to get used to it.

On Debian systems it can be installed with:

#> aptitude install mmv

Answer 5

if you don't have spaces in the filenames:

for f in *.JPG; do mv $f `echo $f | sed 's/JPG$/jpg/'`; done