I must admin I have used, and do use, bi-directional pipes. I like the 
idea of sitting in a select() / poll() for all my IO, sockets, files and 
child/spanwed processes, and using both read() and write() on the one 
socket. To be portable I then have to either;

- use two pipes just for child/spawned process communication
- use socketpair() to ensure bi-directional.

As it happens I tend to go for tha latter as it will work under Win32 as 
well (manual socketpair though) with nonblocking etc.

Just my 2p and just a weak argument (clean code) :)

Lundy


David Laight wrote:
>>In the commercial UNIX world it's been this way for many many years now.
>>I would not be suprised at all if there were not many applications
>>depending on this well documented behaviour.
> 
> 
> At least 15 years....
> 
> There are also likely to be applications that rely on fattach().
> Although posix only requires it for streams, SVR4 allows it for
> any char special or pipe device.
> 
> For the uninitiated, fattach() effectively mounts a fd onto a
> file system node.
> 
> Welcome to the 1980's :-)
> 
> 	David
> 

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