Today I was in need to install 1 single package from the unstable release of Debian in a server installed with the stable release, so what’s the best way to get this done ?
For this example I’ll use the package drush because there are a lot of differences in the versions between the different release of Debian.
But as first thing you must be sure to have all the repository that you want to use in the file /etc/apt/sources.list in these days if you are using a server that uses the stable release (squeeze) you should have something similar to this one:
deb http://debian.fastweb.it/debian squeeze main contrib non-free deb http://debian.fastweb.it/debian wheezy main contrib non-free deb http://ftp.it.debian.org/debian unstable main contrib non-free deb http://security.debian.org/ squeeze/updates main contrib deb-src http://security.debian.org/ squeeze/updates main contrib deb http://www.backports.org/debian squeeze-backports main contrib non-free |
This list defines all the standard repository: stable (squeeze), testing (wheezy) and Sid aka Unstable, we are also defining the backport repository and the security repository.
Now, to know which versions are available for a package that you want to install use the command: apt-cache policy packagename, so using drush as package I get this output:
apt-cache policy drush drush: Installed: (none) Candidate: 3.3-1 0 Version table: 5.7-1 0 100 http://ftp.it.debian.org/debian/ unstable/main amd64 Packages 100 /var/lib/dpkg/status 5.4-1 0 500 http://debian.fastweb.it/debian/ wheezy/main amd64 Packages 4.5-2~bpo60+1 0 650 http://www.backports.org/debian/ squeeze-backports/main amd64 Packages 3.3-1 0 700 http://debian.fastweb.it/debian/ squeeze/main amd64 Packages |
If you wonder what are the numbers at the start of each repository, these are the priority of every source, the higher has more priority and they are read from the file /etc/apt/preferences that on my server contains these information:
Package: * Pin: release a=stable Pin-Priority: 700 Package: * Pin: release a=squeeze-backports Pin-Priority: 650 Package: * Pin: release a=testing Pin-Priority: 600 Package: * Pin: release a=unstable Pin-Priority: 100 |
So by default the system would install the package from the stable release, and in general this is what i want, but this time I want to install the 5.7 version of the package, let’s see how to do this:
First Method
You can use apt-get -t distribution install package with this command you’ll use the named distribution to install the package name and the dependencies, so using
apt-get -t unstable install drush |
Will install drush 5.7-1 0 AND php 5.4.4-9, one of the dependencies of this package.
This could be exactly what you are searching for, but perhaps you just want to have drush from the unstable distribution and keep php at the stable distribution ?
Second Method
To install just drush from the unstable distribution you can use the command: apt-get install drush/unstable the command is similar to the former, BUT there is an important difference this command tell to apt to install ONLY the package drush from the unstable distribution and all its dependencies will be taken from the default distribution; in this case from the stable distirbution, and so at the end of this command you’ll have drush 5.7-1 0 AND php 5.3.3-7+squeeze14
More ways
These 2 ways should cover most of your needs, but it’s also possible to temporary change the priority file or tell apt-get to install a specific version, and I’m sure that there are other ways to achieve this result, as usual there is more than one way to get the result on GNU/Linux and it’s a thing I love of this operating system.
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In general, mixing stable and upstream Debian repos will lead to dependency problems down the road, judging by thousands of posts on the Debian forums by newbies that have done exactly what you advise, only to realize later that many packages are now uninstallable. Debian specifically advises against your method.
A safer method is to download the deb directly from packages.debian.org and use gdebi to try and install it. If there’s dependency issues with the stable libraries, it will refuse to do so.
The very best method, though it’s the most work, is to backport the newer package from the source code against the stable libraries. This does take some skill for some packages, but absolutely will not break anything.
http://forums.debian.net/viewtopic.php?f=16&t=38976
As Steve Pusser already sated, it is not advisable to mix Stable with Testing or Sid. Fortunately, in this case, the package is relatively “independent” and can be installed without much hassle, but in many cases it is necessary to update a core package (like PHP) that would break various installed packages.
The best method is to compile the package using the Stable tree.
I do not understand your APT Preferences. Backports has a priority of 1, yet you gave it 650; and any non-installed package has a priority of 500, but you gave 700 to Stable and 600 to Testing and Sid. Is it not easier to give Testing and Sid a priority of 1, like Backports?
There seems to be a problem with the Testing repository, because you gave it 600 and its Apt-Cache shows that it has 500 (just like any non-configured repository).
One of the European mirrors for Backports should give you a faster connection.