SCCS and make

SCCS is often used with make(1S) to maintain a software project. make provides for automatic retrieval of source files. (Other versions of make provide special rules that accomplish the same purpose.) It is also possible to retrieve earlier versions of all the source files, and to use make to rebuild earlier versions of the project:

$ mkdir old.release ; cd old.release
$ ln -s ../SCCS SCCS
$ sccs get -c"87/10/01" SCCS
SCCS/s.Makefile: 
1.3 
47
.  .  .  
$ make
.  .  .  

As a general rule, no one should check in source files while a build is in progress. When a project is about to be released, all files should be checked in before a build. This ensures that the sources for a released project are stable.