How do I use popen(
The problem with trying to pipe both input and output to anarbitrary slave process is that deadlock can occur, if both
processes are waiting for not-yet-generated input at the same
time. Deadlock can be avoided only by having BOTH sides follow a
strict deadlock-free protocol, but since that requires
cooperation from the processes it is inappropriate for a
popen()-like library function.
The 'expect' distribution includes a library of functions that a
C programmer can call directly. One of the functions does the
equivalent of a popen for both reading and writing. It uses ptys
rather than pipes, and has no deadlock problem. It's portable to
both BSD and SV. See question 3.9 for more about 'expect'.
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