$GIT_DIR usage

Hi, I had a question about $GIT_DIR. That is to say, it doesn't seem to work. I am using Git 1.5.2.4. See the following: (all the commands I tried besides "git-init" failed).

$ export GIT_DIR="`pwd`/.git_public" $ git init warning: templates not found /usr/share//git-core/templates/ Initialized empty Git repository in /home/user/temp/.git_public/ $ echo > new_file $ git add new_file fatal: add must be run in a work tree $ git commit -a fatal: /usr/bin/git-commit cannot be used without a working tree. $ git commit fatal: /usr/bin/git-commit cannot be used without a working tree. $

Is $GIT_DIR not meant to be used this way? Does it have a different purpose / use case, or is this just a bug?

Thanks, Dan