Is there a version control system abstraction for the command-line?

Now that so many small open source projects 开发者_如何学JAVA"ship" via their version control systems, I have dozens of repositories that I need on a frequent basis, often on multiple machines. I'm looking for some kind of way to manage this easily. If I were to design it myself, I would have a file listing all the remote repositories, and a command-line client that automatically pulled from them.

Does this, or some variation on the theme, exist?

mr is designed to let you update multiple repositories as one, and supports a wide range of version control systems:

The mr(1) command can checkout, update, or perform other actions on a set of repositories as if they were one combined respository. It supports any combination of subversion, git, cvs, mercurial, bzr, darcs, cvs, and fossil repositories, and support for other revision control systems can easily be added. (There are extensions adding support for unison and git-svn.)

The only project I know which aims at providing a common interface (called 'command') for all the major VCS is Amp.
But it is still a work in progress and might not be complete enough for your goal.