Journey of a new GNOME 3 Debian packager

With all the buzz around GNOME 3, I really wanted to try it out for real on my main laptop. It usually runs Debian Unstable but that’s not enough in this case, GNOME 3 is not fully packaged yet and it’s only in experimental for now.

I asked Josselin Mouette (of the pkg-gnome team) when he expected it to be available and he could not really answer because there’s lots of work left. Instead Roland Mas gently answered me “Sooner if you help”. 🙂

First steps as a GNOME packager

This is pretty common in free software and for once I followed the advice, I spent most of sunday helping out with GNOME 3 packaging. I have no prior experience with GNOME packaging but I’m fairly proficient in Debian packaging in general so when I showed up on #debian-gnome ( on sunday morning, Josselin quickly added me to the team on

Still being a pkg-gnome rookie, I started by reading the documentation on This is enough to know where to find the code in the SVN repository, and how to do releases, but it doesn’t contain much information about what you need to know to be a good GNOME packager. It would have been great to have some words on introspection and what it changes in terms of packaging for instance.

Josselin suggested me to start with one of the modules that was not yet updated at all (most packages have a pre-release version—usually 2.91—in experimental, but some are still at 2.30).

Packages updated and problems encountered

(You can skip this section if you’re not into GNOME packaging)

So I picked up totem. I quickly updated totem-pl-parser as a required build-dependency and made my first mistake by uploading it to unstable (it turns out it’s not a problem for this specific package). Totem itself was more complicated even if some preliminary work was already in the subversion repository. It introduces a new library which required a new package and I spent a long time debugging why the package would not build in a minimalistic build environment.

Indeed while the package was building fine in my experimental chroot, I took care to build my test packages like the auto-builders would do with sbuild (in sid environment + the required build-dependencies from experimental) and there it was failing. In fact it turns out pkg-config was failing because libquvi-dev was missing (and it was required by totem-pl-parser.pc) but this did not leave any error message in config.log.

Next, I decided to take care of gnome-screensaver as it was not working for me (I could not unlock the screen once it was activated). When built in my experimental chroot, it was fine but when built in the minimalistic environment it was failing. Turns out /usr/lib/gnome-screensaver/gnome-screensaver-dialog was loading both libgtk2 and libgtk3 at the same time and was crashing. It’s not linked against libgtk2 but it was linked against the unstable version of libgnomekbdui which is still using libgtk2. Bumping the build-dependency on libgnomekbd-dev fixed the problem.

In the evening, I took care of mutter and gnome-shell, and did some preliminary work on gnome-menus.

Help is still welcome

There’s still lots of work to do, you’re welcome to do like me and join to help. Come on #debian-gnome on, read the documentation and try to update a package (and ask questions when you don’t know).

Installation of GNOME 3 from Debian experimental

You can also try GNOME 3 on your Debian machine, but at this point I would advise to do it only if you’re ready to invest some time in understanding the remaining problems. It’s difficult to cherry-pick just the required packages from experimental, I tried it and at the start I ended up with a bad user experience (important packages like gnome-themes-standard or gnome-icon-theme not installed/updated and similar issues).

To help you out with this, here’s a file that you can put in /etc/apt/preferences.d/gnome to allow APT to upgrade the most important GNOME 3 packages from experimental:

Package: gnome gnome-desktop-environment gnome-core alacarte brasero cheese ekiga empathy gdm3 gcalctool gconf-editor gnome-backgrounds gnome-bluetooth gnome-media gnome-netstatus-applet gnome-nettool gnome-system-monitor gnome-system-tools gnome-user-share baobab gnome-dictionary gnome-screenshot gnome-search-tool gnome-system-log gstreamer0.10-tools gucharmap gvfs-bin hamster-applet nautilus-sendto seahorse seahorse-plugins sound-juicer totem-plugins remmina vino gksu xdg-user-dirs-gtk gnome-shell gnome-panel dmz-cursor-theme eog epiphany-browser evince evolution evolution-data-server file-roller gedit gnome-about gnome-applets gnome-control-center gnome-disk-utility gnome-icon-theme gnome-keyring gnome-menus gnome-panel gnome-power-manager gnome-screensaver gnome-session gnome-settings-daemon gnome-terminal gnome-themes gnome-user-guide gvfs gvfs-backends metacity mutter nautilus policykit-1-gnome totem yelp gnome-themes-extras gnome-games libpam-gnome-keyring rhythmbox-plugins banshee rhythmbox-plugin-cdrecorder system-config-printer totem-mozilla epiphany-extensions gedit-plugins evolution-plugins evolution-exchange evolution-webcal gnome-codec-install transmission-gtk avahi-daemon tomboy network-manager-gnome gnome-games-extra-data gnome-office update-notifier shotwell liferea epiphany-browser-data empathy-common nautilus-sendto-empathy brasero-common
Pin: release experimental
Pin-Priority: 500

Package: *
Pin: release experimental
Pin-Priority: 150

The list might not be exhaustive and sometimes you will have to give supplementary hints to apt for the upgrade to succeed, but it’s better than nothing.

I hope you find this useful. I’m enjoying my shiny new GNOME 3 desktop and it’s off for a good start. My main complaint is that hamster-applet (time tracker) has not yet been integrated in the shell.

My Debian related goals for 2011

Like last year, here’s a list of Debian related projects that I’d like to tackle this year. I might not do them all, but I like to write them down, I am more productive when I have concrete objectives.

  1. Translate my Debian book into English.
    I will run a fundraising campaign with and if enough people are interested, I will spend a few months with Roland Mas to translate the book. Hopefully this project can be completed until the summer.
  2. Finish multiarch support in dpkg.
    I’m working on this with Guillem Jover right now, thanks to Linaro who is sponsoring my work.
  3. Make deb files use XZ compression by default.
    It’s a simple change in dpkg-deb and it would literally save gigabytes of space on mirrors. It’s particularly important so that single CD/DVD can have a more complete set of software. #556407 (on DAK) needs to be fixed first though and a project-wide discussion is in order. Some archs might want to have a different default.
  4. Be more reactive to review/merge dpkg patches.
    While we welcome help, we have a backlog of patches sitting in the BTS and it happened several times that we failed to review/merge submitted branches in a decent time. It’s very frustrating for the contributor. I already tried to improve the situation by creating the Review/Merge Queue but nobody stepped up to help review and update the patches.
    As I am getting more familiar with the C part of dpkg, I hope to be able to jump in when Guillem doesn’t have the time or the interest.
  5. Implement the rolling distribution proposed as part of the CUT project and try to improve the release process.
    I really want the new rolling distribution but it will inevitably have an impact on the release process. It can’t be done as a standalone project. I would also like to see progress in the way we deal with transitions (see discussion here).
  6. Work more regularly on the developers-reference.
    Hopefully I will be able to combine this with my blog writing activities, i.e. write blog articles on the topics that the developers-reference shall cover and then adapt my articles with some docbook markup.

To the above list, I shall add a few supplementary goals related to funding my Debian work:

  1. Write a 10-lesson course called “Smart Package Management”.
    It will delivered by email to my newsletter subscribers.
  2. Create an information product (most likely an ebook or an online training) and sell it on my blog.
    The precise topic has not yet been defined although I have a few ideas. Is there something that you would like me to teach you? Leave your suggestions in a comment.
  3. By the end of the year, have at least 1/3 of my time funded by donations and/or earnings of my information products.
    More concretely it means 700 € each month or a 9-fold increase compared to the current income level (around 80 €/month mostly via Flattr).

That makes up lots of challenges for this year. You can help me reach those goals, join my Debian Supporters Guild and you’ll be informed every time that I start something new or when you can help in specific ways.

Review of my Debian related goals for 2010

Last year I shared my “Debian related goals for 2010”. I announced that I would not be able to complete them all and indeed I have not, but I have still done more than what I expected. Let’s have a look.

Translate my Debian book into English and get it published: NOT DONE

Or rather not yet done. It’s still an important project of mine and I will do it this year. When I wrote this last year, I expected to find a publisher that would take care of everything but we failed to find a suitable one so we’re going to do it ourselves.

Cleanup the dpkg perl API and create libdpkg-perl: DONE

libdpkg-perl has been introduced with dpkg 1.15.6.

Create dpkg-buildflags: DONE

dpkg-buildflags has been introduced with dpkg 1.15.7. It’s not widely used yet and it won’t really be until debhelper 7 supports it (see #544844). It would be nice to see progress on this front this year.

Ensure the new source formats continue to gain acceptance: DONE

The adoption rate has been steady, it clearly slowed down since the freeze though. I have implemented quite a few features to satisfy the needs of users, like the possibility to unapply the patches after the build, or the possibility to fail in case of unwanted upstream changes.

Design a generic vcs-buildpackage infrastructure to be integrated in dpkg-dev: NOT DONE

I believe it’s something important on the long term but it never made it to my short-term TODO list and it’s unlikely to change any time soon.

Continue fixing dpkg bugs faster than they are reported: PARTLY DONE

We have dealt with many bugs over the year, but we still have 20 more bugs than at the start of last year (370 vs 350). We’re not doing bad compared to many other Debian teams but we can still benefit from some help. Start here if you’re interested.

Enhance our infrastructure to ease interaction between contributors and to have a better view of how each package is maintained: NOT DONE

I am convinced that we need something to have a clearer idea of the commitments made by each contributor. I don’t put the same amount of care in maintaining smarty-gettext that I do on dpkg. If we had a database of the stuff that we know we don’t do well enough, it’s easier to point new contributors towards those.

Anyway, this project is still unlikely to come to the top of my priorities any time soon.

Work on the developers-reference: NOT DONE

We have switched the Maintainer field to to have more review of the changes suggested through the bug tracking system but that has not changed much on the global situation.

I still hope to become more active on it sometimes this year. Maybe by trying to make it more fun and creating the text for some of the wishlist bugs as blog articles first.

Rewrite in C the last Perl scripts provided by the dpkg binary package: DONE

Dpkg 1.15.8 was the first version working without Perl, I announced it in July.

Integrate the 3-way merge tool for Debian changelogs in dpkg-dev: DONE

dpkg-mergechangelogs is part of dpkg-dev since 1.15.7.

I enjoy it regularly. Unfortunately it doesn’t work well for cherry-picks. Would be nice to see this fixed, anyone up to the task? 🙂

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How to create custom RSS feeds with WordPress

WordPress has many alternate built-in feeds: per category, per tag, per author, per search-keyword. But in some cases, you want feeds built with some more advanced logic. Let’s look at the available options.

WordPress advanced built-in feeds

You can create feeds for “unions” or “intersections” of tags, you just have to use a URL like /tag/foo,bar/feed/ (all articles tagged with foo or bar) or /tag/foo+bar/feed/ (all articles tagged with foo and bar).

You can also have feeds excluding a category, although that requires you to know the category identifier (and hardcode it in the URL like this: /?feed=rss2&cat=-123 where 123 is the category id that you want to exclude).

But there’s no simple way to have a feed that excludes articles with a given tag. The best solution found involves creating a custom feed. I’ll show you a variation of this below.

Creating a custom feed

  1. First of, install the Feed Wrangler plugin, it will take care of registering our custom feeds with wordpress.
  2. Go to “Settings > Feed Wrangler” in your WordPress administrative interface and create a new feed, let’s call it “myfeed”.
  3. You should now create a “feed-myfeed.php” file and put it in your current theme’s directory. The initial content of that file should be this:
  4. At this point, you already have a new feed that you can access at /feed/myfeed/ (or /?feed=myfeed). It’s a complete feed like the main one.

Now, we’re going to look at ways to customize this feed. We’re going to do this by changing/overriding the default query that feed-rss2.php’s loop will use.

A feed excluding articles with a tag

If you want to create a feed that excludes the tag “foo”, you could use this:

global $wp_query;
$tag = get_term_by("slug", "foo", "post_tag");
$args = array_merge(
        array('tag__not_in' => array($tag->term_id))

That was relatively easy, thanks to the “tag__not_in” query parameter. Now you can further customize the feed by adding supplementary query parameters to the $args array. The documentation of query_posts details the various parameters that you can use.

A feed excluding articles with a custom field (meta-data)

I went further because I did not want to use a tag to exclude some posts: that tag would have been public even if it was only meaningful to me. So I decided to use a custom field to mark the posts to exclude from my new feed. I named the field “no_syndication” and I always give it the value “1”.

This time it’s not so easy because we have no query parameter that can be used to exclude posts based on custom fields. We’re going to use the “post__not_in” parameter that can be used to exclude a list of posts. But we must first generate the list of posts that we want to exclude. Here we go:

global $wp_query;
$excluded = array();
$args_excluded = array(
    'numberposts'     => -1,
    'meta_key'        => 'no_syndication',
    'meta_value'      => 1,
    'post_type'       => 'post',
    'post_status'     => 'published'
foreach (get_posts($args_excluded) as $item) {
        $excluded[] = $item->ID;
$args = array_merge(
        array('post__not_in' => $excluded)

A feed with modified content

You might want to add a footer to the articles that are syndicated. I use the Ozh’ Better Feed plugin for this but it applies to all your feeds.

You could do that sort of transformation only in your customized feed by using the WordPress filter named the_content_feed.

Here’s a simple example:

function myfeed_add_footer($content) {
        return $content . "<hr/>My footer here";
add_filter('the_content_feed', 'myfeed_add_footer');

I’ll stop here but obviously you have lots of options and many ways to tweak all the snippets above. They have been tested with WordPress 3.0.4.

Note that in all those examples, I took care to not duplicate the code from feed-rss2.php, instead I used include() to execute it. That way my custom feeds will automatically benefit from all the future enhancements and fixes made by the WordPress developers.

But if you have to modify the XML structure of your custom feeds, you can paste the content of feed-rss2.php in your file and change it like you want…