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

My recommendation is to use:

find . -name '*.lua' -exec ex '+%s/\t/  /g' -cwq {} \;

Comments:

1. Use in place editing. Keep backups in a VCS. No need to produce *.orig files. It's good practice to diff the result against your last commit to make sure this worked as expected, in any case.
2. sed is a stream editor. Use ex for in place editing. This avoids creating extra temp files and spawning shells for each replacement as in the top answer.
3. WARNING: This messes with all tabs, not only those used for indentation. Also it does not do context aware replacement of tabs. This was sufficient for my use case. But might not be acceptable for you.
4. EDIT: An earlier version of this answer used find|xargs instead of find -exec. As pointed out by @gniourf-gniourf this leads to problems with spaces, quotes and control chars in file names cf. Wheeler.