Question

I need to remove all trailing whitespaces before changed files will be committed. The question is how to do it?

Answer 1

I don’t believe there’s a good way to just automatically remove trailing whitespace at commit time (and I don’t believe it’d be a good idea to do it if you could).

I’ve used a hook before to reject commits that add trailing whitespace, which worked well for me; create/add the following to .git/hooks/pre-commit and make it executable:

# Work out what to diff against
if git rev-parse --verify HEAD >/dev/null 2>&1
then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

# If there are whitespace errors, print the offending file names and fail.
exec git diff-index --check --cached $against --