Revision Control

The ASTERIX development system uses sccs, the UNIX source code control system. This is done for two very different reasons,

• Almost unbelievably the text archive format is not portable between SunOS and Solaris, and not up-datable between Solaris and OSF. A container is required for text modules, and updates to tar archives are not universally supported.

• We need some way of preserving old versions of code which accessible with resorting to system backups.

Typical mistakes using SCCS include,

• Making a read only copy of a file, editing it (because jed allows this), and replaceing it. Effect is to change object module correctly but does not update the source archive. Result is that next time you rebuild the library the change goes away!

• Deleting the writable copy of a module. Simply re-extract the module using the sccs get -r mode (a simple sccs get fails because SCCS believes the module is write locked), change the protection using chmod w+ and then replace it.

If you make a change which subsequently turns out to have been ill-advised then you can recover old versions by discarding subsequent revisions. See the manual for details. You can also recover the whole archive to a particular date.

It is important to realise that only the development system uses SCCS -- Starlink just get tar files containing the source modules and build it from those. This duality is controlled by the AST_SYS_DEV environment variable which causes the mk script to make alternate token substitutions. Starlink build ASTERIX without setting this variable, we define a value for it (which is itself irrelevant) in the sysdev procedure.