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Unix in a Nutshell, 4th Edition by Arnold Robbins

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General RCS Specifications

This section discusses:

  • Keyword substitution

  • Keywords

  • Example values

  • Revision numbering

  • Specifying the date

  • Specifying states

  • Standard options and environment variables

Keyword Substitution

RCS lets you place keyword variables in your working files. These variables are later expanded into revision notes. You can then use the notes either as embedded comments in the input file or as text strings that appear when the output is printed. To create revision notes via keyword substitution , follow this procedure:

  1. In your working file, type any of the keywords listed below.

  2. Check the file in.

  3. Check the file out again. Upon checkout, the co command expands each keyword to include its value. That is, co replaces instances of:

                    $
                    keyword
                    $

    with:

    $keyword:value$.
  4. Subsequent check-in and check-out of a file updates any existing keyword values. Unless otherwise noted below, existing values are replaced by new values.

Many commands have a -k option that provides considerable flexibility during keyword substitution.

Keywords

$Author$

Username of person who checked in the revision.

$Date$

Date and time of check-in.

$Header$

A title that includes the RCS file's full pathname, revision number, date, author, state, and (if locked) the person who locked the file.

$Id$

Same as $Header$, but exclude the full pathname of the RCS file.

$Locker$

Username of person who locked the revision. If the file isn't locked, this value is empty.

$Log$

The message that was typed during ...

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