SubVersion is a modern VersionControlSystem that aims to replace CVS. Of the numerous CVS replacements, SubVersion is quite possibly the most similar to CVS in CommandLine interface and has a stable support community, making it a good choice if you wish to move away from CVS.
It lifts the limitations of CVS by versioning MetaData and dealing with commits as a unit, called a change set. How does this help?
The CommandLine client, analogous to cvs(1) and with very similar use for the most part, is called svn. svn help provides a list of all commands and global options. svn help command provides help about the specific command. Unfortunately, there is no ManPage to speak of.
See also: