Convert bulk ebook on seprate filetype *.mobi to *.epub using calibre and terminal on ubuntu

If you have a folder full of mobi files in separate folders, and you want to convert to epub format, do this

mkdir mobi (where a copy of just the .mobi files will be sent
shopt -s globstar
cp **/*.mobi mobi/
cd mobi
for book in *.mobi; do echo "Converting $book"; ebook-convert "$book" "$(basename "$book" .mobi).epub"; done 
mkdir ../epub
mv *.epub ../epub

Now calibre can be used to put them on your nook, or just directly copy and paste.