What is the Git equivalent for revision number?

Good or bad news for you, that hash IS the revision number. I also had trouble with this when I made the switch from SVN to git.

You can use "tagging" in git to tag a certain revision as the "release" for a specific version, making it easy to refer to that revision. Check out this blog post.

The key thing to understand is that git cannot have revision numbers - think about the decentralized nature. If users A and B are both committing to their local repositories, how can git reasonably assign a sequential revision number? A has no knowledge of B before they push/pull each other's changes.

Another thing to look at is simplified branching for bugfix branches:

Start with a release: 3.0.8. Then, after that release, do this:

git branch bugfixes308

This will create a branch for bugfixes. Checkout the branch:

git checkout bugfixes308

Now make any bugfix changes you want.

git commit -a

Commit them, and switch back to the master branch:

git checkout master

Then pull in those changes from the other branch:

git merge bugfixes308

That way, you have a separate release-specific bugfix branch, but you're still pulling the bugfix changes into your main dev trunk.

A Bash function:

git_rev ()
{
    d=`date +%Y%m%d`
    c=`git rev-list --full-history --all --abbrev-commit | wc -l | sed -e 's/^ *//'`
    h=`git rev-list --full-history --all --abbrev-commit | head -1`
    echo ${c}:${h}:${d}
}

outputs something like

$ git_rev
2:0f8e14e:20130220

That is

commit_count:last_abbrev_commit:date_YYmmdd

The problem with using the git hash as the build number is that it's not monotonically increasing. OSGi suggests using a time-stamp for the build number. It looks like the number of commits to the branch could be used in place of the subversion or perforce change number.