Cleanest way to checkout an earlier tag for read-only purposes in Git

Question

I have a working tree on my local machine, and a remote repository as well. Let's say I want to quickly build an earlier version of my project at a known tag without disturbing the current state of the working version. My inclination is to checkout a separate tree, which seems to go like in this question:

http://stackoverflow.com/questions/791959/how-to-use-git-to-download-a-particular-tag

With a clone from the remote repository followed by a checkout in there. But the clone does a lot of work and pulls down all the revision state. Is there any lightweight way of saying "grab me the current state of the world at this commit/tag and spray it into this directory?" (Further revision control not necessary-- it's "read only" as far as Git should be concerned.)

Maybe not-- just checking.

Thanks.

Answer 1

Sounds like you're looking for git-export: http://stackoverflow.com/questions/160608/how-to-do-a-git-export-like-svn-export

Answer 2

Try

git checkout -b new_branch [previous_tag]

Answer 3

If it's all local, you can do this:

mkdir /path/to/test-tree
cd /path/to/repo
git read-tree <tag>
git checkout-index -a --prefix=/path/to/test-tree/  # don't forget the last slash

# read-tree copies content into the index
# to restore it:
git read-tree HEAD

That's assuming you don't care about the other tree having any git information at all. If you want it to, you could use the git-new-workdir script, which basically creates a clone, except populating the .git directory with symlinks back to the original repo, so that it takes no extra disk space. It's a nice approach - no extra disk space, and you can use one repo for development, one for testing, etc.