How do I find patches in debian packages?

Question

How are the patches in debian/patches obtained?

Is this

diff -Nurp folder/original folder1/new

enough?

Answer 1

This usually depends on the type of patch system which the package uses.

There are 3 types of patch systems for Debian packages:

1) Quilt (most widely used)

2) Cdbs + Simple Patchsys

3) dpatch

All patch systems store patches in debian/patches. You can use the what-patch command in package ubuntu-dev-tools to find out which patch system a package is using.

Introduction of Quilt:

Quilt patches can be easily manipulated using the quilt command from a terminal. The quilt command is a part of package quilt

This page will help you getting along with quilt. Also check out the quilt manoage by running

man quilt

in a terminal.

Now for cdbs + simple-patchsys:

These patches are manipulated commonly by a script called cdbs-edit-patch in package cdbs . You can edit patches like this:

cdbs-edit-patch *PATCHNAME*

You can add new patches like this:

cdbs-edit-patch *NEW_PATCHNAME* *PREV_PATCHNAME*

Where *PREV_PATCHNAME* is the name of the patch after which *NEW_PATCHNAME* will apply.

dpatch:

dpatch patches can be manipulated using the script dpatch-edit-patch in package dpatch . The usage of dpatch-edit-patch is exactly the same as cdbs-edit-patch above.

Answer 2

The section "Modify upstream files" of http://raphaelhertzog.com/2011/07/04/how-to-prepare-patches-for-debian-packages/ explains how those patches are created when the patch system in use is quilt (which is the most common case thanks to the new source format "3.0 (quilt)").