Difference Between HEAD and HEAD:HEAD

Question

What is the difference between HEAD and HEAD:HEAD notation in git commands e.g.:

git fetch origin HEAD:HEAD

I can even understand what git fetch origin HEAD does, however, not using the other notation.

I would be grateful for any kind of help or advice.

Answer 1

The notation "HEAD:HEAD" in Git commands like "git fetch origin HEAD:HEAD" may look a bit confusing, but it is essentially a shorthand for a common operation. Let me break it down for you:

HEAD (without the colon):

• When you use HEAD without a colon in a Git command, it typically refers to the currently checked out commit in your local repository. In other words, it points to the commit that your working directory and the "HEAD" branch are currently at.

HEAD:HEAD (with the colon):

• In the context of a fetch operation, such as "git fetch origin HEAD:HEAD," the "HEAD:HEAD" notation is specifying a source and destination reference for the fetch operation. In this notation: -The part before the colon represents the source, which is typically a reference to a commit or a branch in the remote repository (in this case, "origin"). -The part after the colon represents the destination, which is typically a reference in your local repository.

When you use "git fetch origin HEAD:HEAD," it is effectively saying: "Fetch the commit that 'HEAD' in the 'origin' remote repository is pointing to and update the local 'HEAD' to that same commit."