???

Q:
Can you give me any information about how to make a program like the
"talk" command in UNIX?

Thank you for your help!
A:
You can program it in any language that you like and fits. For example C,
Perl or some other language.

You have to implement the communication between the two programs. The
simplest solution is to write the messages sent to a directory into files
and see if there is any new file there and dump the content to the screen.

I hope this answer helps.

Regards,
Peter