Compare and apply a diff / patch recursively

Hacky way to keep config files in sync when there’s a new version of some software.

Caveat : probably completely wrong, may not pick up config entries added in the new version, etc. But, works for me right here right now ;-)

So let’s say we have two folders:

confluent-4.1.0
confluent-4.1.1

Same structures, different versions. 4.1.0 was set up with our local config in ./etc, that we want to preserve. We can use diff to easily see what’s changed:

diff -r confluent-4.1.0/etc confluent-4.1.0/etc

But this only tells us what changed. Nicer is to automagically apply it.

Let’s run this from the folder in which we’re going to apply the changes:

cd confluent-4.1.1/etc

Run the diff, and write the results to a file:

diff -ur . ../../confluent-4.1.0/etc > 4.1.1.patch 

Now apply it:

patch -p0 < 4.1.1.patch

Of course, you took a backup first before you did that, just in case something broke… right?