suspend-tty

[Eli Zaretskii <eliz@gnu.org>]

Does anyone know what is the purpose of suspend-tty?  (Please don't
tell "to stop I/O from/to a terminal", since that just repeats the
name of the function.)  IOW, under what circumstances would a Lisp
program want to do that, and what could be then done with the terminal
which Emacs ``suspended''?

I tried invoking suspend-tty on a GNU/Linux machine, and the terminal
just got hang, the only thing I could do is abort Emacs.  (If I had
another tty open in the same session, I understand I could resume-tty,
but that doesn't really answers my question.)  I thought suspend-tty
would leave the terminal free for use by other programs, but it sounds
like I misunderstood?

The only non-trivial user of suspend-tty is server.el, but the new
functionality that uses it is completely undocumented, both in the
code, in NEWS and in the manuals, and the semantics of using this API
evaded me.

Can someone give a hint?

TIA