There are several source code management systems used in the Unix community:
The Source Code Control System. SCCS is the original Unix source code management system. It was developed in the late 1970s for the Programmer’s Workbench (PWB) Unix systems within Bell Labs. It is still in use at a few large longtime Unix sites. However, for a long time it was not available as a standard part of most commercial or BSD Unix systems, and it did not achieve the widespread popularity of other, later systems. (It is still available with Solaris.) SCCS uses a file storage format that allows it to retrieve any version of a source file in constant time.
The Revision Control System. RCS was developed in the early 1980s at Purdue University by Walter F. Tichy. It became popular in the Unix world when it was shipped with 4.2 BSD in 1983. At the time, Berkeley Unix was the most widely used Unix variant, even though to get it, a site had to have a Unix license from AT&T.
RCS is easier to use than SCCS. Although it has a number of related commands, only three or four are needed for day-to-day use, and they are quickly mastered. A central repository is easy to use: you first create a directory for the sandbox. In the sandbox, you make a symbolic link to the repository named RCS, and then all the developers can share the repository. RCS uses a file format that is optimized for retrieving the most recent version of a file.
The Concurrent Versions System. CVS was initially ...