Usage: ptyexec <cmd>

Connects the stdio of <cmd> to a pseudoterminal.

Returns something like:

MASTER: /dev/ptyqa
SLAVE:  /dev/ttypa

You should extract the SLAVE device and open it or pass it to the
application for use.

E.g. the i/o of <cmd> could be a fake a "serial" device for a communications
app, say pppd.