Compare and apply a diff / patch recursively

Published by in Diff, Patch at https://rmoff.net/2018/06/07/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?

Robin Moffatt

Robin Moffatt works on the DevRel team at Confluent. He likes writing about himself in the third person, eating good breakfasts, and drinking good beer.