Automatically keeping "last modified" up to date

[Daniel J S. <dan...@ie...>]

I just built the most recent version of gnuplot and noticed that the 
"last modified" date in the intro refers back to 2012 and is manually 
entered.  Why can't that automatically be generated?  It would be nice 
to do this so that when one builds/installs the latest version, upon 
launching the program it is immediate clear that the install process was 
successful by looking at the "last modified" date.

Here are some approaches that could be tried:

1) There is this configure.in file containing:

dnl $Id: configure.in,v 1.332 2013/07/18 23:22:17 sfeam Exp $

Is that file somehow generated by the CVS/repository to reflect the most 
recent modification of the repository?  If so, that would be great as it 
would also contain a time stamp.  Could write a script to search for 
that and define LAST_MODIFIED in some header file using the extracted 
"2013/07/18 23:22:17" string.

2) Is there some way during make to get the most recent date of all the 
pertinent files?  "make" does date checking, so perhaps there is a make 
variable/macro that reflects that.

3) Similar to #2, we could maybe write an OS script that does the same 
thing by looking for the date of the most recent file in the source tree.

4) Ethan keeps the ChangeLog up to date.  It would be easy to search for 
the most recent date near the top of the file and use that as a 
definition for LAST_MODIFIED.

Dan