hook - In Git, how can I write the current commit hash to a file in the same commit

Question

I'm trying to do a fancy stuff here with Git hooks, but I don't really know how to do it (or if it's possible).

What I need to do is: in every commit I want to take its hash and then update a file in the commit with this hash.

Any ideas?

Answer 1

I would recommend doing something similar to what you have in mind: placing the SHA1 in an untracked file, generated as part of the build/installation/deployment process. It's obviously easy to do (git rev-parse HEAD > filename or perhaps git describe [--tags] > filename), and it avoids doing anything crazy like ending up with a file that's different from what git's tracking.

Your code can then reference this file when it needs the version number, or a build process could incorporate the information into the final product. The latter is actually how git itself gets its version numbers - the build process grabs the version number out of the repo, then builds it into the executable.