Installs 5 commands that process a git directory tree. Directories containing a file called .ignore are ignored. The git-commitAll command commits all changes to each repository in the tree. The git-evars command writes a script that defines environment variables pointing to git repos. The git-exec command executes a bash expression on children of a directory, or a list of directories. The git-replicate command writes a script that clones the repos in the tree, and adds any defined remotes. The git-update command updates each repository in the tree.