L. Peter Deutsch writes:
 > As far as I know (echoing Adam Richter's earlier comment), all Linux vendors
 > distribute GNU Ghostscript, but it's my impression that most other Unix
 > sites (and most non-Unix users) download and install Aladdin Ghostscript,
 > and that Linux users who become aware of the existence of Aladdin
 > Ghostscript often do so as well.  (I don't know how to get real numbers
 > about this: I'm basing this on the Ghostscript version numbers in problem
 > reports I get from the Net.)

This is a specific example of the larger problem of knowing how many
people are actually using your freed software.  Freed software
businesses have just as much interest in "sales" as any other
business.  I assert that profit is proportional to use in the freed
software market just as in the proprietary software market.  So, usage
figures are important.

But how to get them?  I have no really good idea.  Dan Bernstein has
the following at the end of his qmail INSTALL instructions:

	That's it! To report success:
	       % ( echo 'First M. Last'; cat `cat SYSDEPS` ) \
		 | mail djb-qst@koobera.math.uic.edu
	Replace First M. Last with your name. If you have questions
	about qmail, contact qmail@pobox.com.

This doesn't track the number of users who install, then remove the
software, nor the ones who install but don't report success.  I don't
know how proprietary software vendors deal with the difference between
sales and use.

-- 
-russ <nelson@crynwr.com>  http://www.crynwr.com/~nelson  | Freedom is the
Crynwr Software supports freed software | PGPok |   primary cause of peace.
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