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• Launchpad Entry: dpkg-triggers

• Packages affected: dpkg, many

Summary

A dpkg trigger is a facility that allows events caused by one package but of interest to another package to be recorded and aggregated, and processed later by the interested package. This feature simplifies various registration and system-update tasks and reduces duplication of processing.

Detailed design with worked deployment examples

The dpkg triggers feature was extensively discussed on debian-dpkg, and the final version of the specification can be found here:

• http://lists.debian.org/debian-dpkg/2007/04/msg00076.html

UI Changes

The implementation and use of triggers is not intended to affect the user interface. There are some new error states involved but these will typically occur in the same kind of situations as existing package failures (eg, maintainer script failures).

Release Note

• A feature ("triggers") was implemented in dpkg to allow packages to cut down on duplicated processing during installations and upgrades, and some packages updated to use the new facility.

Test/Demo Plan

Check that initramfs generation happens exactly once during the execution of

sudo dpkg -i udev.deb initramfs-tools.deb

Documentation

• http://manpages.ubuntu.com/manpages/karmic/en/man5/deb-triggers.5.html

• http://www.seanius.net/blog/2009/09/dpkg-triggers-howto/

CategorySpec