Unix in a Nutshell, 4th Edition

Building a Better CVS

When discussing Subversion’s features, it is often helpful to speak of them in terms of how they improve upon CVS’s design. Subversion provides:

Directory versioning

CVS only tracks the history of individual files, but Subversion implements a “virtual” versioned filesystem that tracks changes to whole directory trees over time. Files and directories are versioned.

True version history

Since CVS is limited to file versioning, operations such as copies and renames—which might happen to files, but which are really changes to the contents of some containing directory—aren’t supported in CVS. In CVS, you cannot delete a versioned file and then create a new file of the same name with different contents without inheriting the history of the old—perhaps completely unrelated—file. With Subversion, you can add, delete, copy, and rename both files and directories. Every newly added file begins with a fresh, clean history all its own, even if the filename was previously used.

Atomic commits

A collection of modifications either goes into the repository completely, or not at all. This allows developers to construct and commit changes as logical chunks, and prevents problems that can occur when only a portion of a set of changes is successfully sent to the repository.

Versioned metadata

Each file and directory has a set of properties—keys and their values—associated with it. You can create and store any arbitrary key/value pairs. Properties are versioned over time, just like ...