Etckeeper puts /etc under revision control, git by default, which then behaves like a normal git repository.

All our machines use EtcKeeper, which should be installed early in the setup process. (Typically among the first packages installed after performing the system installation and first boot).

1. Installation

apt-get install etckeeper

etckeeper init
cd /etc
git commit -am "Initial commit"

2. Usage

The most useful Git commands we most often use are:

 git status                      (list of files and their Git states)
 git log                         (see commit dates & commit msgs)
 git log -p                      (see commits with diff included)
 git add FILE...                 (add FILE to git)
 git diff                        (see any differences since last commit)
 git commit -am "Commit message" (commit your changes after modification)
 git checkout FILE               (override FILE with version from last commit)

Each time you make a change to a file or set of files and are happy with it, commit your change.

It is tempting to use git commit -am "Message ..." which commits all files (-a) and provide the commit message on the command line (-m "..."). While that is tolerable practice, listing specific files on the command line and providing a properly formatted Git commit message is preferred over the "bulk" -am switches.

The -a switch very often commits other changed files that had nothing to do with your commit, such as modified by not committed changes of other admins or files automatically generated/modified by DomTool or system scripts. Those automatically-modified files should be handled in one of the following ways, in order of preference from highest to lowest:

• If they change often (such as hosts.deny/hosts.allow), move them to /var/tmp/ and provide a symlink from /etc/, registering only the symlink in Git.
• Periodically committing them (just them) with the appropriate commit message (i.e. "Periodic commit of modified files")

• Removing them from Git (copy them aside, invoke git rm FILE; git commit -am "Remove FILE", and copy them back to expected location

3. Notes

EtcKeeper is better than custom solutions as it also adds apt hooks, so the files are added and commited to git automatically before/after apt-get installs.