apt-get install debian-wizard

5 Free Software projects to support with Flattr

February 1, 2011 by Raphaël Hertzog

GNU Wget (Flattr link) is the famous command line utility used to download files over HTTP. Nice to see some GNU projects on Flattr!
Pingus (Flattr link) is a nice Lemmings clone. It’s a game where you have to guide a group of penguins through dangerous levels to reach an exit.
Download Statusbar (Flattr link) is a Firefox extension that replaces the download window by a small status bar embedded in the main browser window.
PCSC-Lite (Flattr link) is a middleware to access a smart card using SCard API (PC/SC).
Mathomatic (Flattr link) is general-purpose Computer Algebra System.

This article is part of the Flattr FOSS project.

Debian Cleanup Tip #1: Get rid of useless configuration files

January 31, 2011 by Raphaël Hertzog

If you like to keep your place clean, you probably want to do the same with your computer. I’m going to show you a few tips over the next 4 weeks so that you can keep your Debian/Ubuntu system free of dust!

Over time the set of packages that is installed on your system changes, either because you install and remove stuff, or because the distribution evolved (and you upgraded your system to the latest version).

But the Debian packaging system is designed to keep configuration files when a package is removed. That way if you reinstall it, you won’t have to redo the configuration. That’s a nice feature but what if you will never reinstall those packages?

Then those configuration files become clutter that you would rather get rid of. In some cases, those files lying around might have unwanted side-effects (recent example: it can block the switch to a dependency-based boot sequence because obsolete init scripts without the required dependencies are still present).

The solution is to “purge” all packages which are in the “config-files” state. With aptitude you can do aptitude purge ~c (or aptitude purge ?config-files). Replace “purge” by “search” if you only want to see a list of the affected packages.

If you want a machine-friendly list of the packages in that state, you could use one of those commands (and then pass the result to apt-get if you don’t have aptitude available):

$ grep-status -n -sPackage -FStatus config-files
[...]
$ dpkg-query -f '${Package} ${Status}\n' -W | grep config-files$ | cut -d" " -f1
[...]

Note that grep-status is part of the dctrl-tools package.

Of course you can also use graphical package managers, like Synaptic. Click on the “Status” button on the bottom left, then on “Not installed (residual config)” and you have a list of packages that you can purge. You can select them all, right click and pick “Mark for Complete Removal”. See the screenshot below. The last step is to click on “Apply” to get the packages purged.

Synaptic purging residul config files

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3 ways to not clutter your Debian source package with autogenerated files

January 28, 2011 by Raphaël Hertzog

It’s quite common that the upstream build system generates/updates some files but does not clean them up properly when you call make clean. In that case, when you rebuild the package a second time in the same tree, the generated Debian source package will contain those changes.

You usually don’t want those changes. They make your package harder to review because they contain unneeded modifications (either directly in the .diff.gz with the old source format, or in a new patch in debian/patches/debian-changes-<ver> with the “3.0 (quilt)” source format).

I’ll show you 3 ways to avoid this problem. They are all workarounds, the proper fix would be to improve the upstream build system to really clean up the generated files. This is usually possible for files that are “created”, but it’s much more cumbersome for files that are “updated” (you would have to keep a backup of the original file so that you can restore it).

The traditional fix

Instead of relying on the upstream build system to do the work, we modify the clean target in debian/rules to remove the files that are left-over. Since “debian/rules clean” is always called before a source package is built, those generated files are not included as changes compared to what upstream provided.

A common work-around: always build from a clean state

As you have noted, the problem only happens when you build (source and binaries) twice in a row in the same tree. Some VCS-helper tools always build the Debian package in a temporary tree which is exported from the VCS. This is the case of svn-buildpackage by default and of git-buildpackage if you use its --git-export-dir option.

I don’t like this solution because it solves the problem only for the maintainer. Anyone else who is working on top of the package without using the same VCS-helper tool would be affected by the problem.

A new way to avoid the problem

Since it’s now possible to store dpkg-source options in the source package itself, we can conveniently have everybody use the --extend-diff-ignore option. It tells dpkg-source to ignore some files when checking whether we have made changes to upstream files.

For example if you want to ignore changes made on the files “config.sub”, “config.guess” and “Makefile” you could put this in debian/source/options:

# Don't store changes on autogenerated files
extend-diff-ignore = "(^|/)(config\.sub|config\.guess|Makefile)$"

You need to know a bit about Perl regular expressions since that’s what is used by dpkg-source to match the filenames to exclude.

Note that this approach always works, even when you can’t remove the file. So it saves you having to make a backup of the unmodified file just to be able to restore it before the next build.

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My Debian related goals for 2011

January 26, 2011 by Raphaël Hertzog

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.

Translate my Debian book into English.
I will run a fundraising campaign with Ulule.com 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.
Finish multiarch support in dpkg.
I’m working on this with Guillem Jover right now, thanks to Linaro who is sponsoring my work.
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.
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.
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).
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:

Write a 10-lesson course called “Smart Package Management”.
It will delivered by email to my newsletter subscribers.
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.
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.

The traditional fix

A common work-around: always build from a clean state

A new way to avoid the problem

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