Called by parent programs:
vc-autoinit.setl (Section A.3 [vc-autoinit.setl])
vc-clear.setl (Section A.6 [vc-clear.setl])
Source code: *
-- Echo either the contents of the file containing the configured
-- serial port address, or a default port address.
const conf_file = `vc-comport.conf';
[com_port] := split (getfile conf_file ? `16#3f8');
putchar (com_port);