This guide introduces usage of quilt for managing patches to Debian packages.
It describes how to create,
modify,
apply and unapply patches with quilt.
This is a work in progress. Please send any comments or ideas to <dmn@debian.org>.
quilt helps managing a series of patches that a Debian package maintainer needs applied to upstream source when building the package.
It is similar to dpatch and cdbs's simple-patchsys in that the patches are kept as a series of files in debian/patches.
quilt uses a special directory for keeping patches.
Unfortunatelly,
that directory is ./patches/ by default.
For Debian packages ./debian/patches/ is far more comfortable.
To flawlessly fix this,
add export QUILT_PATCHES=debian/patches to ~/.quiltrc (creating that file if needed).
quilt manages the series of patches as a stack.
You push to it (apply a patch) and pop from it (unapply a patch).
A special file,
debian/patches/series,
contains the list of all patches to be applied.
quilt applies patches in the order they are listed in that file.
Instead of using the quilt command,
you can use git to manage the patch series applied on top of the upstream source tree.
To do so,
use gbp-pq(1).
If you choose to go this way,
you can skip reading the rest of this document.
quilt works in the source tree.
There's no copying large trees around.
There's also no need to always keep the source tree clean of unapplied changes just to be able to extract a diff with Git.
To achieve this,
however,
quilt needs to know which files are contained in each patch.
The workflow is as follows:
quilt that you start working on a given patchquilt that you're doneAt first this may sound complicated, but you can do it! In a nutshell, you speak to your patch system so it knows what you're doing, and it handles the details.
Here are a few examples of working with quilt.
Note that most of the commands below have plenty of options so reading quilt man page is a good idea.
To create a patch,
run quilt new $patch_name.
If you want .patch extension,
you need to give it explicitly.
This creates a new patch entry in debian/patches. This patch also becomes the topmost or current patch. This is the patch that is at the top of the stack.
Now choose what file you want to change in that patch and run quilt edit $file.
quilt notes the current state of the file and launches your $EDITOR so you can edit the file.
Repeat the quilt edit command for every file you want to be changed by that patch.
When you're finished,
run quilt refresh.
This compares the noted state of the edited files with their present state,
and produces a patch in debian/patches.
Note that this patch is currently applied.
Check it with quilt applied.
If the package is already being maintained in the pkg-perl Git repository,
it is necessary to tell Git that you have added new files.
You can do this with git add debian/patches ; git commit.
Now that we have the patch applied,
let's play with it.
quilt pop unapplies the topmost patch.
quilt push applies the next patch in the series.
You may see the list of unapplied patches with quilt unapplied.
To edit a patch,
you have to first make it current (be on the top of the stack of applied patches).
If the patch is already applied (but not the top),
run quilt pop $patch_name; if it is not,
run quilt push $patch_name.
Now that the patch is on the top of the stack,
run quilt edit $file as before.
You can edit files that were already in the patch and you can edit new files.
When you're done,
remember to tell this to quilt by running quilt refresh.
quilt delete deletes,
quilt rename renames a patch.
There are a lot more.
See the manual page.
Unless 3.0 (quilt) source format is used (see below),
quilt needs to be added to Build-Depends.
Note that Build-Depends-Indep (for arch:all packages) is not appropriate as quilt is needed by the clean target.
Note: Patches should be unapplied before committing other changes to Git! If you forget, don't worry, Lintian will issue a warning to remind you.
Since patches are used so often,
the "3.0 (quilt)" source package format supports them by default.
A running build system will use quilt if it's available and dpkg-source can apply patches otherwise.
To test your package,
you can do this:
$ apt-get source libacme-foo-perl
$ mkdir -p libacme-foo-perl-0.1/debian/source
$ echo "3.0 (quilt)" >libacme-foo-perl-0.1/debian/source/format
$ dpkg-source -b libacme-foo-perl-0.1
$ dpkg-source -x libacme-foo-perl-0.1-1.dsc
$ cd libacme-foo-perl-0.1 && debuild -us -uc
quilt push -f # force rejections
quilt edit files-with-rejections
quilt refresh
quilt push
quilt refresh
By default, quilt saves patches that look like the output from diff. This means they include timestamps for each changed file. However, patch doesn't need any of that data to apply the patch and it has the unfortunate side effect of causing every file header line of the patch to change each time someone runs quilt refresh.
To use the simplest headers in the patch, add:
QUILT_DIFF_ARGS="--no-timestamps --no-index -pab"
QUILT_REFRESH_ARGS="--no-timestamps --no-index -pab"
to ~/.quiltrc. The next time you quilt refresh a patch, quilt will remove the extraneous information.
If upstream has made a change that conflicts with a patch, one normally force-applies the patch (with quilt push -f patch) and then looks at the resulting *.rej file to see what part of the patch failed. By default, rejected hunks come out in unified diff format if the input patch was of that format, otherwise in ordinary context diff form. If you're using patches in context diff format, you can tell quilt to create unified context diffs for the *.rej files by putting:
QUILT_PATCH_OPTS="--reject-format=unified"
in your ~/.quiltrc.
Copyright (c) 2007-2012 by the individual authors and contributors noted above. All rights reserved. This document is free software; you may redistribute it and/or modify it under the same terms as Perl itself
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