GIT correct $Id keyword expansion

A set of hooks for GIT, which do real version number incrementing when a file that contains a well formed $Id string is committed. These hooks have absolutely no effect on files not containing a $Id string. A major feature of these hooks is the fact that they are compatible with GIT branch names and store the branch name from which a file is committed in the $Id string.

The format of a clean well formed $Id <version> strings for these hooks is very similar to those used by RCS/CVS/SVN, namely full stop separated pairs of major and minor versions:

* the first string is the major version number in the master branch.
* even strings are consecutive version numbers in the branch.
* odd strings identify branches (branch names or numbers).

The following are a sequence if $Id strings for the file xx.c after a series of 3 edit/commits in the ‘master’ branch followed by 2 edit/commits in branch ‘bx’ followed by an edit/commit in branch ‘by’:

$Id: xx.c 1.1 $
$Id: xx.c 1.2 $
$Id: xx.c 1.3 $
$Id: xx.c 1.3.bx.1 $
$Id: xx.c 1.3.bx.2 $
$Id: xx.c 1.3.bx.2.by.1 $

This is how the $Id text is stored in the GIT archive after each commit. After ‘smudging’, which is applied to the file in the working directory after a git commit/fetch/checkout, the last $Id would look like this:

$Id: xx.c 1.3.bx.2.by.1 30e82ef 2016-04-03 14:48:24 +1000 Joe Blow $

This automatic method if $Id keyword expansion shows the current file name, the branch in which an instance of a file was edited and its individual version number within that branch.  This information is embedded in the text of a file in a manner, which is fully compatible with GIT. After smudging, the $Id also shows the commit SHA-1, the date and the author of the file instance. The $Id information in each file provides an independent file oriented view, which can be regarded as a belts and braces approach to handling files in GIT.

I will introduce these hooks later in this post.

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