Get the current Git branch name or commit hash if detached [duplicate]

Question

Is there a single command that will print the current branch (e.g. master) if there is one, or the commit hash if it is detached? The purpose is to give me something to write down so I can later execute git switch <branch_or_commit> to get back to where I started.

This is to be used programmatically, so no scraping of git status, Bash pipes or whatever. The answer needs to use the "plumbing" commands, which have guarantees about the format and stability of their output.

Also I should note that there are many many questions asking for each of these thinks individually, but not together. PLEASE THINK BEFORE CASUALLY MARKING THIS AS A DUPLICATE.

Here are the things I have tried. The closest is actually cat .git/HEAD.

Command	Output on a branch	Output when detached
git rev-parse HEAD	cedbe9...	cedbe9...
git rev-parse --abbrev-ref HEAD	master	HEAD
git symbolic-ref --short HEAD	master	fatal: ref HEAD is not a symbolic ref
cat .git/HEAD	ref: refs/heads/master	cedbe9...
git branch --show-current	master	(no output)
your answer here	master	cedbe9...

Answer 1

Impossible with exactly one command but possible with two:

git symbolic-ref -q --short HEAD || git rev-parse HEAD

Get the current branch; but if detached get the hash.