The 'terminal_crosslink' server allows exactly two clients to communicate with
each other using the 'Terminal' interface. Data sent to the server gets stored
in a buffer of 4096 bytes (one buffer per client). As long as the data to be
written fits into the buffer, the 'write()' call returns immediately. If no
more data fits into the buffer, the 'write()' call blocks until the other
client has consumed some of the data from the buffer via the 'read()' call. The
'read()' call never blocks. A signal receiver can be used to block until new
data is ready for reading.

Example
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An example run script 'terminal_crosslink.run' can be found in the 'os/run'
directory.
