This week, while helping out the DebConf 15 team with some proofreading, I encountered a kind of diff I've never worked with before. A wdiff, or word diff, is intended for displaying word differences between text files. In the context where you are editing free-form text, rather than something like code, it makes a lot more sense than a more traditional unified or copied diff.

So far, so good! But, unfortunately, neither I nor the people who I was working with were able to find any tool out there that actually lets you apply a wdiff patch to a file - or even to blindly discard or accept all the changes inside a wdiff file.

As with most problems, it's nothing a sufficiently gross application of Perl can't solve. In case anyone in the future runs into this problem, I'm including the little Perl one-liner that will take a wdiff file on stdin and output the document with all changes applied. It's not pretty, and I haven't tested it that thoroughly, so use it with caution.

perl -ne '$_ =~  s/ ?\[-(?:[^\]]+)-\]//g; $_ =~ s/ ?\{\+([^\}]+)\+\}/ $1/g; print $_'