input*) (stdout *standard-output*) 
<BR>(stderr *error-output*) (args nil) </EM>[function]

<DL COMPACT>
<DT> 
<DD> 
forks a process, replaces its stdin, stdout, and stderr streams to specified ones,
and exec's "exec" with the args arguments.
piped-fork is roughly equivalent to
<code> (xfork exec :stdin (unix:pipe) :stdout (unix:pipe))</code>
Though xfork returns an io-stream to stdin and stdout with their
directions reversed,
it is not always useful unless they are pipes. 
The name of this function, xfork 