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Say you're running a server and you don't want to upgrade to Testing (Squeeze) from Stable (Lenny) to just install a required package or two.

What's the best way of installing only certain packages from Testing?

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Many people seem to be afraid of mixing stable with testing, but frankly, testing is fairly stable in its own right, and with proper preferences and solution checking, you can avoid the "stability drift" that puts your core packages on the unstable path.

"Testing is fairly stable??", you ask. Yes. In order for a package to migrate from unstable to testing, it has to have zero open bugs for 10 consecutive days. Chances are that, especially for the more popular packages, somebody is going to submit a bug report for an unstable version if something is wrong.

Even if you don't want to mix the environments, it's still nice to have the option there in case you run into some thing that requires a newer version than what is in stable.

Here's what I recommend for setting this up:

First, create the following files in /etc/apt/preferences.d:


Package: *
Pin: release l=Debian-Security
Pin-Priority: 1000


Package: *
Pin: release a=stable
Pin-Priority: 900


Package: *
Pin: release a=testing
Pin-Priority: 750


Package: *
Pin: release a=unstable
Pin-Priority: 50


Package: *
Pin: release a=experimental
Pin-Priority: 1

(Don't be afraid of the unstable/experimental stuff here. The priorities are low enough that it's never going to automatically install any of that stuff. Even the testing branch will behave, as it's only going to install the packages you want to be in testing.)

Now, creating a matching set for /etc/apt/sources.list.d:


deb         stable/updates  main contrib non-free
deb         testing/updates main contrib non-free


deb stable main contrib non-free
deb-src stable main contrib non-free
deb    stable main contrib non-free
deb-src    stable main contrib non-free

testing.list: Same as stable.list, except with testing.

unstable.list: Same as stable.list, except with unstable.

experimental.list: Same as stable.list, except with experimental.

You can replace the mirror with whatever you want. I'd recommend using netselect-apt to figure out the fastest mirror, and use that for your first choice. The can be used as a backup. It's also important to use the terms stable, testing, unstable, etc., instead of squeeze, wheezy, sid, etc., since stable is a moving target and when it comes time to upgrade to the latest stable, apt/aptitude will figure that out automatically.

You can also add a oldstable in sources.lists.d and preferences.d (use a priority of 1), though this moniker will tend to expire and disappear before the next stable cycle. In cases like that, you can use and "hardcode" the Debian version (etch, lenny, etc.).

To install the testing version of a package, simply use aptitude install lib-foobar-package/testing, or just jump into aptitude's GUI and select the version inside of the package details (hit enter on the package you're looking at).

If you get complaints of package conflicts, look at the solutions first. In most cases, the first one is going to be "don't install this version". Learn to use the per-package accept/reject resolver choices. For example, if you're installing foobar-package/testing, and the first solution is "don't install foobar-package/testing", then mark that choice as rejected, and the other solutions will never veer to that path again. In cases like these, you'll probably have to install a few other testing packages.

If it's getting too hairy (like it's trying to upgrade libc or the kernel or some other huge core system), then you can either reject those upgrade paths or just back out of the initial upgrade altogether. Remember that it's only going to upgrade stuff to testing/unstable if you allow it to.

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Thanks, used this method and everything is working like I expected it to! – Brad F Jacobs Sep 12 '12 at 16:56
I'm trying to use this, but I'm not able to resolve any dependencies at all. It seems like neither apt-get, neither aptitude will look for the dependencies in the testing repos. Is there a way to solve that? – Tamás Szelei Nov 19 '12 at 16:28
Did you run apt-get update after you created the config files? – Flow Apr 30 '13 at 16:04
I also have the same dependency problem... – draw Jun 15 '13 at 18:22
I'm getting (what seems to me) inconsistent behaviours using this method. "apt-get install -t testing appX" does not give the same as "apt-get install appX/testing" (see )- I'm guessing that it's just about the way this method causes the priorities to be resolved, even though it not intuitive to me? – eugenevd Dec 8 '14 at 11:45

In /etc/apt/apt.conf.d add the following file


APT::Default-Release "stable";

in /etc/apt/sources.list.d - add urls for testing / unstable sources


deb    stable main contrib non-free
deb-src    stable main contrib non-free

deb         stable/updates  main contrib non-free


deb    testing main contrib non-free
deb-src    testing main contrib non-free

deb         testing/updates  main contrib non-free


apt-get update

and then install what you need with

apt-get -t testing install something

Be very very careful if you install stuff that has plenty of dependencies. Preferably don't do this on production.

You can as well try your luck at backports or similar repository.

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+1 Great answer – David Pashley Jun 9 '09 at 8:01
Wow. That was quick. I was posting so as to share the information I'd just come across! Nice one! – gyaresu Jun 9 '09 at 8:05
I've never actually used the apt.conf method before. It seems simpler that the preferences file method, but gives you less precise control. - Coops – Coops Jun 9 '09 at 8:37
Answer needs upgrading; this config will break things completely now that squeeze has become stable and lenny has become oldstable. – El Yobo Feb 15 '11 at 3:05
in newer debian releases there is no apt.conf file, instead edit /etc/apt/apt.conf.d/70debconf – Hayden Thring Mar 22 '13 at 7:35
up vote 42 down vote accepted


Define the default level that the system should 'safe-upgrade' to in the /etc/apt/preferences file:
man apt_preferences

There's a lot you can do with apt_preferences but for the sake of simplicity...

I needed to install a single package (autoMysqlBackup) that was only available in Testing. The solution was to add the following to /etc/apt/preferences:

Explanation: Uninstall or do not install any Debian-originated
Explanation: package versions other than those in the stable distro
Package: *
Pin: release a=stable
Pin-Priority: 900

Package: *
Pin: release o=Debian
Pin-Priority: -10

With multiple repositories added to /etc/apt/sources.list aptitude will now only upgrade to your specified release even though the later release repos are listed (in this case 'stable').

deb lenny main
deb-src lenny main
deb squeeze main
deb-src squeeze main

So to install that package, all you have to do is:

$ aptitude install -t testing packageName
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This is a good method too, not at quick as easy as apt.conf, but lets you control all your different sources in a relative manner. – Coops Jun 9 '09 at 8:39
This is too complicated for the task... Using APT::Default-Release does set the pin priority of the release to 990 (similar to how you set it to 900) and the negative pinning for the rest is not really needed... during dist-upgrades the stable package have priority anyway and as soon as you list something explicitly on the command line, its negative pinning priority will be mostly ignored. – Raphaël Hertzog Jun 9 '09 at 9:54
I'm not sure how to reply to you @Raphael. It seems a very elegant way of doing things. I've used apt pinning before years ago but I never really 'got' it. The examples I've used above are straight from the apt_preferences man page. – gyaresu Jun 9 '09 at 10:27
Confirm this works fine on squeeze – tomfanning Mar 7 '12 at 11:48
@Lothar: It does work on Debian 6. Just because the file doesn't exist doesn't mean it doesn't work. Just create the file and add the settings. Quote from the man page: "If there is no preferences file or if there is no entry in the file that applies to a particular version then the priority assigned to that version is the priority of the distribution to which that version belongs." – rzetterberg Oct 15 '12 at 12:11

The debian documentation is extensive in the subject and I strongly advise to dig in as it will truely unveil the beauty of the debian system.

Have a look at How to keep a mixed system, it will explain all you need tio know.

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This seems to be the same method used in the answer by @pQd, so it doesn't apply to debian >=6.0. Also the link title says "obsolete documentation" now. Also mostly link only answer. – dequis Apr 12 '14 at 9:08

For what it's worth, the general advice I've always seen is "Don't mix stable with anything." Most of the mixed systems tutorials are for mixing testing and unstable.

The reasoning seems to be that if you mix stable with testing, very basic packages (like libc6) will require updates (in order to install software from testing), and once these basic packages move to testing, the whole system can drift that way.

Here are two alternatives:

  1. Use Backports.
  2. Install a source line from testing, and try to build the later version you want from source.
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I agree. I just tried updating libdvdread4 from testing because of a bug in the version in wheezy/stable. It wants to bring in the latest libc though. So I just grabbed the source package for libdvdread4 from stable and patched it with the 1 line source change and rebuilt it. Way better than pulling in all sorts of packages from testing. Now all packages are still the "stable" ones and I just have the 1-line change I need. – dgrant Sep 12 '13 at 16:58

Another way, that could prevent installing too many dependences from Testing or Sid, is this: you tell apt-get to get the source of the package from Testing or Sid and create a package for your system using Debian tools (no need to manually tinker with sources).

Quoting from here:

How do I backport a sid package to testing or stable?

Install the Debian source (and the development tools, especially debhelper, devscripts, and build-essential), and then build the package.

Step by step:

add a deb-src line for sid to your sources.list

apt-get update

apt-get build-dep PACKAGE_NAME

apt-get -b source PACKAGE_NAME 

The resulting debs should be in the current directory and can be installed with dpkg -i the.deb.

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I have been doing it for an extended period of time to be confident in saying it is safe enough and can be made convenient. With the below setup stable version will installed by default, however Aptitude will also allow you to choose backported or unstable version if so desired:

enter image description here

There are four things that need to be edited, the default pinning release needs to be set, the sources need backports and unstable added, lowering the pinning priority of backports/unstable packages, and the aptitude display settings needs to be modified to display pinning.

  • Create a '/etc/apt/apt.conf.d/10defaultrelease' and make it's contents as follows:
Apt::default-Release "stable";
  • Edit your '/etc/apt/sources.list' to add unstable and backports sources so it looks something like this:
# deb cdrom:[Debian GNU/Linux 6.0.0 _Squeeze_ - Official Multi-architecture amd64/i386 NETINST #1 20110205-14:45]/ squeeze main

deb squeeze main
deb-src squeeze main

deb squeeze/updates main
deb-src squeeze/updates main

# squeeze-update, previously know as 'volatile'
deb squeeze-updates main
deb-src squeeze-updates main

# squeeze backports
deb squeeze-backports main

# unstable
deb unstable main
deb-src unstable main

# non free ex. sun java
#deb squeeze non-free
#deb-src squeeze non-free
  • Edit etc/apt/preferences pinning file - if the file doesn't exist do create it.
# Package pinning priorities
# See and
# In nut shell highest PIN gets installed
# Pining default are as follow which are in addition to our settings:
#   990 - for version that are not installed but DO belong to our `APT::Default-Relase "stable"` setting.
#   500 - for versions that are not installed and do not belong to the target release
#   100 - for packages that already installed, this also means other versions of same package
#     1 - for experimental packages; packages with "NotAutomatic: yes"
# Our Pinnings
#   400 - backports that can safely be installed without the need to update other packages
#    50 - unstable packages, install forced in the details screen, can result in conflicts

Package: *
Pin: release n=squeeze-backports
Pin-Priority: 400

Package: *
Pin: release a=unstable
  • Create '/etc/apt/apt.conf.d/100guiconf' and to setup Aptitude so it display pinning information.
Aptitude::UI::Package-Display-Format "%c%a%M %p %Z %v %V %i";
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Just an update that in addition to the above I have settled on running all my system packages from the 'testing' development repositories. So in source.list it should say code name jessie instead of squeeze. Debian's policy testing is near stable and packages have been almost as new as from the unstable repository. I'm running out of space here so please take a look at:,, and; the last two are additional repository sources. – Daniel Sokolowski Aug 8 '13 at 13:20

If your selection of packages is more involved or the installation will be repeated on multiple machines, you might consider setting up a private repository that mirrors a subset of the official repositories. This requires a bit of work to configure the repository but the reward is easy to maintain with a bare minimum of configuration on each client and repeatable results when doing dozens of installations. I find this helpful even when only one or two packages are being installed, and use this method for automating and maintaining cloud installs. A single server on a cheap VPS can handle dozens of private repositories.

To configure your private repository server:

# Install aptly.
apt-get install aptly

# Create local mirror (choose a source mirror near you).
aptly mirror create -filter="mirror-contains-no-packages" stretch-roundcube stretch main

# Configure filters for local mirror.
aptly mirror edit -filter="Name (% roundcube*)" stretch-roundcube

# Update local mirror.
aptly mirror update stretch-roundcube

# Drop previously published repositories and mirrors, if running these commands in a script.
aptly publish drop stretch

# Drop snapshot, if running these commands in a script.
aptly snapshot drop stretch-roundcube

# Create new snapshot.
aptly snapshot create stretch-roundcube from mirror stretch-roundcube

# Publish snapshot.
aptly publish snapshot -architectures=i386,amd64 -distribution=stretch -component=roundcube -label="Your Name" -origin="Your Name" stretch-roundcube

Then configure your web server of choice to serve the static repository files. Possibly protect the repository with a security certificate and basic authentication.

To automatically maintain your private repository and pull in updates from upstream, put the above in a script and run from a cron job.

To configure your client machine, on your client machine:

# Configure private repository without authentication.
echo 'deb stretch roundcube' > /etc/apt/sources.list.d/

# Configure private repository with authentication.
echo 'deb stretch roundcube' > /etc/apt/sources.list.d/
apt-get install apt-transport-https

# Update.
apt-get update

# Install package.
apt-get install roundcube

To maintain your client machine and pull in all of your private repository updates, on your client machine:

# Update.
apt-get update

# Upgrade.
apt-get upgrade
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