reading and writing to another process

[chongo at nsc.UUCP]

how do i do the following:

   write a program foo which establishes both a read and a write to pipe
   to the program bar.  bar is in binary form.  bar was written to read/write
   to stdin and stdout. (i.e., i cant modify bar to do the job)

and:

   same setup except that i want the program foo to read stderr of bar too.

chongo /\../\