Git Is Not Magic¶
I'm bored. Let's make a git repository out of whole cloth.
Git repos are stored in .git:
fakegit$ mkdir .git
They have a “symbolic ref” (which are text files, see
to the currently checked-out branch. Let's use
master. Branches are refs
fakegit ((unknown))$ echo 'ref: refs/heads/master' > .git/HEAD
The have an object database and a refs database, both of which are simple
gitrevisions). Let's also enable the reflog,
because it's a great safety net if you use history-editing tools in git:
fakegit ((ref: re...))$ mkdir .git/refs .git/objects .git/logs fakegit (master #)$
__git_ps1, at least, is convinced that we have a working git repository.
Does it work?
fakegit (master #)$ echo 'Hello, world!' > hello.txt fakegit (master #)$ git add hello.txt fakegit (master #)$ git commit -m 'Initial commit' [master (root-commit) 975307b] Initial commit 1 file changed, 1 insertion(+) create mode 100644 hello.txt fakegit (master)$ git log commit 975307ba0485bff92e295e3379a952aff013c688 Author: Owen Jacobson <email@example.com> Date: Wed Feb 6 10:07:07 2013 -0500 Initial commit
Should you do this? Of course not. Anywhere you could run these commands,
you could instead run
git init or
git clone, which set up a number of
other structures, including
.git/config and any unusual permissions options.
The key part here is that a directory's identity as “a git repository” is
entirely a function of its contents, not of having been blessed into being by
You can infer a lot from this: for example, you can infer that it's “safe” to move git repositories around using FS tools, or to back them up with the same tools, for example. This is not as obvious to everyone as you might hope; people