Build (backport) an newer Ubuntu package to run on an older Ubuntu version

[jdong]

You are running the tried-and-true Dapper stable release. You notice that Edgy has a newer version of a package you want. What do you do? Well, prior to this, your would head over to the Backports folks and ask for the package. Some packages are deemed by Backporters to be too bleeding-edge or incompatible to be considered for backporting to Dapper. Now what? Welcome prevu! prevu is like your personal Backports developer, building backports with just a single command.

This is a quick guide to using prevu. We will use gdebi as an example package.


1. Get Prevu! Debs are available at http://sourceforge.net/project/showf...kage_id=206140

2. Edit your /etc/apt/sources.list. You need a deb-src line for the development distro of Ubuntu, such as:

deb-src http://archive.ubuntu.com/ubuntu feisty main restricted universe multiverse

Of course, run apt-get update afterwards.

3. Initialize prevu. You need to run sudo prevu-init when you install prevu for the first time. You don't need to run this again -- only the first time.

4. Build package. Run prevu gdebi
5. Wait patiently. Sit and twiddle your thumbs while your machine compiles away.

6. When completed, look in /var/cache/prevu/edgy-debs. There, you will find freshly generated deb packages! This location is also an APT repository, which can be added to your sources.list like so:

deb file:/var/cache/prevu/edgy-debs ./

Replace edgy with whatever distro you are running.


Note that not all packages will build. If you don't know how to fix it to build, you probably shouldn't try to do it, because chances are you'll screw up your computer

Also, note that building our own backports is an unsupported thing to do. Please do not bug Ubuntu developers about your broken system or packages if prevu could be the cause.


By default, prevu will build debs for the current distro version you are running. If you would like to build for another distro, just run, for example, DIST=breezy prevu gdebi. Note you need to run DIST=breezy prevu-init first.


Filing bugs
Prevu is hosted on Launchpad. Please file bugs to launchpad, product 'prevu'.

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Uninstallation:

Prevu does take up some space. Mine takes up around 100MB of space. Depending on how many packages you have, /var/cache/pbuilder/aptcache might be quite full, too. To remove prevu:

1. Uninstall the prevu package
2. Run sudo rm -rf /var/cache/prevu
3. Run sudo rm /var/cache/pbuilder/aptcache/*

[matthew]

When I have free time I'll play around with it and will file any bugs I find on Launchpad. Thanks for doing this!

[jdong]

I have uploaded a new version of prevu that does not need the build command to be executed as root. This prevents malicious build scripts from screwing with your system.

Note the new .deb download link. After installing the update, run sudo prevu-update to effect the changes. Now, you can just do prevu gdebi, no sudo, but you need to be in the admin group.

Note that sudo is _still_ used to enter the build environment, but root access is dropped as soon as it's possible.

[domino]

Thanks for this tut! I was able to build gdebi but I'm not sure I got it to build correctly. Can anyone provide the MD5 for the two?

dcdd3ff33fd849bb2f2aca62a4772695  gdebi_0.1.6ubuntu1~6.06prevu1.tar.gz

f57d9a92178be9683ff4fe3bea3d7c2c  gdebi_0.1.6ubuntu1~6.06prevu1_all.deb

I'm also try to build the Edgy version of firefox-themes-ubuntu (2.0b2) but it keeps building the older firefox version. Any clue?

[jdong]

I get:

e32a3c1206811bdbb57276b066e7db03  gdebi_0.1.6ubuntu1~6.06prevu1_all.deb

As far as building firefox-themes-ubuntu, it seems like it first needs human-icon-theme. This is a two-step backport, and prevu 0.2.1 and below do not support it yet. Please wait for prevu 0.2.2 to be released.

Subscribe to bug https://launchpad.net/products/prevu/+bug/63255 for notification.

When upgrading prevu, you need to run "sudo prevu-update". You also need to run this command between two-step backports for the debs repository to refresh.

[domino]

Thanks for the prompt reply. It looks like I'm not building correctly since our checksum don't match. I'm thinking I'll need to retry the steps again. Thanks for the heads up on firefox-themes-ubuntu and I'll wait for an updated prevu version.

[jdong]

I rebuilt and re-posted version 0.4.1-0ubuntu1 on Sourceforge. This new release fixes two significant issues, and users are encouraged to upgrade:

(1) Prevu always copies the sources to a temporary working directory. Any sources you unpack will not be modified (this prevents prevu from inserting unwanted changelog entries into your own work)

(2) Prevu now invokes pdebuild differently, which prevents some erroneous build failures due to build-deps not being present on the host. (for example, the absence of cdbs causes lots of packages to fail backporting even though they backport fine)

[foxy123]

I've got a problem with version 0.4.1. It works fine and reports building a package:

dpkg-deb: building package `dvd+rw-tools' in `../dvd+rw-tools_6.1-2ubuntu1~6.06prevu1_i386.deb'.
 dpkg-genchanges
dpkg-genchanges: not including original source code in upload
dpkg-buildpackage: binary and diff upload (original source NOT included)
Copying back the cached apt archive contents
 -> unmounting dev/pts filesystem
 -> unmounting proc filesystem
 -> unmounting /var/cache/prevu/src/5849 filesystem
 -> unmounting /var/cache/prevu/dapper-debs filesystem
 -> cleaning the build env
    -> removing directory /var/cache/prevu/builds/5929 and its subdirectories
** Success!. You can find source packages and .debs at /var/cache/prevu/dapper-debs **

but /var/cache/prevu/dapper-debs is empty

I tried a couple of times and even removed /var/cache/prevu and reinitialised prevu, still no avail. Should I file a bug?

[jdong]

That is a known and fixed bug with the initial 0.4.1 release. It's been fixed, and the 0.4.1 package has been re-released. Please re-download the package from Sourceforge.

[foxy123]

Originally Posted by jdong That is a known and fixed bug with the initial 0.4.1 release. It's been fixed, and the 0.4.1 package has been re-released. Please re-download the package from Sourceforge.

thanks a lot, it fixed it!