How to retrieve the hash for the current commit in Git?

Question

I'm currently busy migrating away from the versioncontrol part of Team Foundation Server to Git. (Why I'm migrating away is a different story ;^) However, I would like to retain (for now) the ability to link Git changesets to workitems stored in TFS.

I already wrote a tool (using a hook from Git) in which I can inject workitemidentifiers into the message of a Git changeset.

However, I would also like to store the identifier of the Git commit (the hash) into a custom TFS workitem field. This way I can examine a workitem in TFS and see what Git changesets are associated with the workitem.

How can I easily retrieve the hash from the current commit from Git?

Answer 1

Use git rev-list --max-count=1 HEAD

Answer 2

To turn arbitrary extended object reference into SHA-1, use simply git-rev-parse, for example

git rev-parse HEAD

or

git rev-parse --verify HEAD

Sidenote: If you want to turn references (branches and tags) into SHA-1, there is git-show-ref and git-for-each-ref.