How can I convert tabs to spaces in every file of a directory?

Question

How can I convert tabs to spaces in every file of a directory (possibly recursively)?

Also, is there a way of setting the number of spaces per tab?

Answer 1

To convert all Java files recursively in a directory to use 4 spaces instead of a tab:

find . -type f -name *.java -exec bash -c 'expand -t 4 {} > /tmp/stuff;mv /tmp/stuff {}' \;