On Thu, Jan 10, 2013 at 09:57:30PM +0000, Vinay Sajip wrote:
My point was that the GnuPG usage looked like an example where fds other than 0, 1 and 2 might be used by design in not-uncommonly-used programs. From a discussion I had with Barry Warsaw a while ago, I seem to remember that there was other software which relied on these features. See  for details.
From the "dpkg" man page:
--command-fd n Accept a series of commands on input file descriptor n. Note: additional options set on the command line, and through this file descriptor, are not reset for subsequent commands executed during the same run.