Alan D. Salewski on 6 Feb 2010 07:37:08 -0800

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Re: [PLUG] Ubuntu -- selectively updating from unstable

On Sat, Feb 06, 2010 at 01:50:31AM -0500, John Karr spake thus:
> Is there a clean and simple way to make apt take just certain packages
> from unstable? (in this case anything PERL). 

You basically want to use pinning. The comments in the files below
explain how this works; they basically "pin" your system to stable, but
allow you to easily pull in packages from testing and unstable.


// The 'Default-Release' specifies the default "target release"
// used by apt-get and friends. By default it is undefined, but
// by specifying it here we can better control the default behavior
// of the tools with regard to running a mixed stable/testing/unstable
// system.
// The notion of a "target release" works in concert with the
// "pinning" rules we've set up in /etc/apt/preferences
// For more info on this stuff, see section 8.2.1 "Pinning releases with APT"
// in Martin F. Krafft's _The_Debian_Book_ (1st Ed., 2005).
// Also:
//     apt.conf(5)
//     apt_preferences(5)
//     apt-cache(8), particularly the 'apt-cache policy' command
APT::Default-Release "stable";


Explanation: Modifies APT's idea of which packages should be installed.
Explanation: In general, we're running a 'stable' distribution, but want
Explanation: to periodically pull in a package from either 'testing' or
Explanation: 'unstable'.
Explanation: Once we've pulled a package in from 'testing', however, we do
Explanation: not want to have to keep manually looking for testing updates
Explanation: of it. Hence the 'testing' archive has a priority less than
Explanation: the 'stable' archive, but above 100 (the value APT automatically
Explanation: assigns to an already installed package), and also above 500
Explanation: (the value APT automatically assigns to any package available
Explanation: for upgrade or installation, if not overridden here).
Explanation: Packages pulled from 'unstable' must always be pulled manually;
Explanation: we do not want churn there to affect us, even though we like
Explanation: to pull in the odd package or three.
Explanation: For an excellent write-up on the motivation for this and how
Explanation: it all hangs together, see section 8.2.1 "Pinning releases with APT"
Explanation: in Martin F. Krafft's _The_Debian_System_ book (1st Ed., 2005).
Explanation: See apt_preferences(5) for the specifics on the contents of
Explanation: this file.
Package: *
Pin: release a=stable
Pin-Priority: 900

Package: *
Pin: release a=testing
Pin-Priority: 800

Package: *
Pin: release a=unstable
Pin-Priority:  80


a l a n   d.   s a l e w s k i   
                        Bruce is mad at me
                  you ask who the hell is bruce?
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