Git-author
Git-author is a new built-in tool for git to extract accurate line-level authorship information. Git-author is implemented with a branch of mainstream git of version v1.7.11. However, git-author is not based on any particular feature of git v1.7.11 and should be compatible with any version of git.
It is easy to install and use git-author. All needed to do is to go into the git directory in this repository and make this specific version (v1.7.11) of git with git-author built in. By adding this version of git to your $PATH evironment variable, you can start to use git-author.
A detailed usage of git-author can be found at "git/Documentation/git-author.txt". The source code of git-author can be found at "git/builtin/author.c".