Integrating with Git: A Field Guide

Pretty much everything you might want to do to a Git repository when writing +tooling or integrations should be done by shelling out to one git command or +another.

Finding Git's trees

Git commands can be invoked from locations other than the root of the work +tree or git directory. You can find either of those by invoking git +rev-parse.

To find the absolute path to the root of the work tree:

git rev-parse --show-toplevel
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This will output the absolute path to the root of the work tree on standard +output, followed by a newline. Since the work tree's absolute path can contain +whitespace (including newlines), you should assume every byte of output save +the final newline is part of the path, and if you're using this in a shell +script, quote defensively.

To find the relative path from the current working directory:

git rev-parse --show-cdup
+

This will output the relative path to the root of the work tree on standard +output, followed by a newline.

For bare repositories, both commands will output nothing and exit with a zero +status. (Surprise!)

To find a path to the root of the git directory:

git rev-parse --git-dir
+

This will output either the relative or the absolute path to the git +directory, followed by a newline.

All three of these commands will exit with non-zero status when run outside of +a work tree or git directory. Check for it.

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