[Tugindia] Using variable definitions from another auxiliary file

[Kannan Moudgalya]

Duvvuri Venu Gopal wrote:
> I assume it is possible. Keep both your books in one .tex file using 
> the \includeonly and \include commands.
> First compile the Part I of the book. (at this run use \includeonly and include all the Part I .tex files)
>
> During the second run use \includeonly and include the .tex files of Part II.
>
> This should work.
>
> Venu Gopal
>   
I do not want to do this.  The source file for the book is quite 
complicated with several subdirectories and so on.  I would not want to 
change it. 

My original question remains: How do I use an existing .aux file from a 
different source for the current compilation.

Kannan