etckeeper is a tool, packaged in Debian, that lets you track revisions to /etc in a Git repository. Here's how to install and configure it.
You can download etckeeper from the url above, but it's probably best to get it from a Debian repository. Since I run etch on my server, that repository would have to be backports.org. To add it:
Add deb http://www.backports.org/debian etch-backports main contrib non-free to your /etc/apt/sources.list
Run: # wget -O - http://backports.org/debian/archive.key | apt-key add - to add the key for that archive, and then run # apt-get update
Once you have backports.org available, you can now install etckeeper:
# apt-get install etckeeper git-core metastore -t etch-backports
A git of at least 1.5.4 is needed, which isn't available in stock etch, so it's also needed from backports.org. etckeeper also requires a number of other dependencies, including python, and mercurial (even though we won't be using it).
Once installed, etckeeper is not automatically configured, so let's do that. First, we need to initialize it:
# cd /etc # etckeeper init # git add . # etckeeper commit 'Initial commit' # git gc
This adds the contents of /etc, recursively, and packs the git repository.
The etckeeper package configures itself to run on pre- and post-install when apt or dpkg install a package, so automatic changes to /etc will be tracked automatically.
Manual changes can be tracked with regular git commands after editing. For example:
# vim /etc/resolv.conf # git commit -a -m 'Added new nameserver entry'