To include a keyword string you simply include the
relevant text string, such as $Id$
, inside the
file, and commit the file. CVS will automatically
expand the string as part of the commit operation.
It is common to embed the $
Id$ string in
the source files so that it gets passed through to
generated files. For example, if you are managing
computer program source code, you might include a
variable which is initialized to contain that string.
Or some C compilers may provide a #pragma ident
directive. Or a document management system might
provide a way to pass a string through to generated
files.
The ident
command (which is part of the RCS
package) can be used to extract keywords and their
values from a file. This can be handy for text files,
but it is even more useful for extracting keywords from
binary files.
$ ident samp.c samp.c: $Id: samp.c,v 1.5 1993/10/19 14:57:32 ceder Exp $ $ gcc samp.c $ ident a.out a.out: $Id: samp.c,v 1.5 1993/10/19 14:57:32 ceder Exp $
SCCS is another popular revision control system.
It has a command, what
, which is very similar to
ident
and used for the same purpose. Many sites
without RCS have SCCS. Since what
looks for the character sequence @(#)
it is
easy to include keywords that are detected by either
command. Simply prefix the keyword with the
magic SCCS phrase, like this:
static char *id="@(#) $Id: ab.c,v 1.5 1993/10/19 14:57:32 ceder Exp $";
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