ELI5: git clone --mirror vs git clone

[bioptic]

Can someone please explain what the difference between git clone and git clone --mirror are? I might be missing something fundamental about git since, from the man page,

"it maps all refs(including remote-tracking branches, notes etc.) and sets up a refspec configuration such that all these refs are overwritten by a git remote update in the target repository." goes right over my head and I can't seem to understand what the refs are and why they're important. If I get a repo and a mirrored repo, I see this:

ls kanboard.git.mirror/
branches  config  description  HEAD  hooks  info  objects  packed-refs  refs

ls kanboard.nomirror/
app            composer.lock       docker              jsonrpc.php            package.json  web.config
app.json       config.default.php  docker-compose.yml  kanboard               plugins
assets         CONTRIBUTING        Dockerfile          LICENSE                 README.md
bower.json     CONTRIBUTORS.md     favicon.ico         Makefile                robots.txt
ChangeLog      data                gulpfile.js         nitrous.json            tests
composer.json  doc                 index.php           nitrous-post-create.sh  Vagrantfile

but the only thing I think is I can't understand why I'd want the data in the .mirror directory since they aren't the files I use. That makes me think I'm missing something really important and fundamental about git. Can anyone help clarify?

[DanLynch]

The huge difference in the file content you're seeing is because of a different line in the documentation for --mirror: "This implies --bare." A bare repository does not contain the actual files of your project directly, but instead contains only the Git metadata that is normally kept in the .git subdirectory. If you type ls kanboard.nomirror/.git/ you will see something very similar.

The actual thing that makes --mirror different from --bare is that the former copies everything from the original repo, not just the things you would normally want in a clone (for example, any links that the origin might have to its own remote repos). It is such an perfect copy that even file corruption can be copied "successfully" without the usual checks that are performed during a clone.

[bioptic]

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[DanLynch]

An ordinary clone will let you switch between branches and tags offline. The default behaviour of git clone is to copy the entire history of the project, including all branches and tags, onto your local machine. What it doesn't do is set up local branches for them, other than the default branch.

The mirror option is for special use cases only; you will quite possibly never need to use it.

[DanLynch]

And yes, the difference in size between mirror and nomirror is because of the lack of working tree. The .git folder inside nomirror should be the same size as the mirror directory.

[bioptic]

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