how to read AND write the same popen()?

[Clifford B Miller]

Under a System V environment (Silicon Graphics 3.2.1 IRIX specifically),
I want to use popen(3) as both an input and output filter.  In other words,
I want to be able to write out to a pipe from popen("cmd","r") and also be
able to capture the output that comes from that command (through another
stream).  I would like to avoid having to write a temporary file because
my application may require a *LARGE* amount of data to be written through
this filter, and I really don't need or want it saved to disk since this
could easily eat all my disk space.  Any suggestions?  Please e-mail to
cliff at research.nec.com (any hint at all would be appreciated, even if I
have to abandon "popen").
 Clifford B. Miller, Research Associate / Systems Administrator
 NEC Research Institute, 4 Independence Way, Princeton, NJ  08540
 Internet: cliff at research.nec.com		phone: (609) 951-2688
 UUCP: ...princeton!necserve!cliff