How can you remove all of the trailing whitespace of an entire project? Starting at a root directory, and removing the trailing whitespace from all files in all folders.
This worked for me in OSX 10.5 Leopard, which does not use GNU sed or xargs.
find dir -type f -print0 | xargs -0 sed -i.bak -E "s/[[:space:]]*$//"
Just be careful with this if you have files that need to be excluded (I did)!
You can use -prune to ignore certain directories or files. For Python files in a git repository, you could use something like:
find dir -not -path '.git' -iname '*.py'