Bidirectional pipe for unix shells

Use twinpipe to start two processes from the unix shell, so that the processes talk to each other via stdout and stdin.

For example, you could use it to start two ppp processes which need to talk to each others (for VPN solutions).

Twinpipe starts the two processes (shell commands) and makes sure that one's stdout is another's stdin.

Two versions are included: A C-language version and shellscript-version.
The shellscript-version uses a named pipe (fifo) to do the trick, and the C-language version just creates two pipes and executes the programs.
Example of usage: twinpipe 'echo a;head -n 1 >&2' 'echo b;echo c'

The package, when compiled, also builds a usleep shell utility, which takes only one argument: microsecondcount, and expectedly sleeps the wanted duration. Example: usleep 200000 (sleeps 0.2s).

twinpipe (the shellscript version and the C version) have been written by Joel Yliluoma, a.k.a. Bisqwit,
and is distributed under the following terms:

* No warranty. You are free to modify this source and to
* distribute the modified sources, as long as you keep the
* existing copyright messages intact and as long as you
* remember to add your own copyright markings.
* You are not allowed to distribute the program or modified versions
* of the program without including the source code (or a reference to
* the publicly available source) and this notice with it.

$ make
$ su
# make install

The official home page of twinpipe is at http://oktober.stc.cx/source/twinpipe.html .
Check there for new versions.