Re: [Sbcl-devel] tty-name

[Harald Hanche-O. <ha...@ma...>]

+ Carlos Agon <Car...@ir...>:

| i want to use the function
| 
| sb-thread:make-listener-thread
| 
| but i don't know what is a tty-name I supose that it is something
| like *stdout* but i can not get a pathname from it

In which case, maybe you don't want to use it after all.  I don't mean
to sound facetious, but this is a function that seems to require a
certain amount of expertise to use it properly.  Let me try to put
this in perspective:

It could be that you have a serial port on your computer, and you wish
to control your Lisp from that serial port.  The serial port might
have a name like /dev/ttyd0, which you might pass (as a string) to
sb-thread:make-listener-thread.

That is of course an unlikely scenario.  But ttys come in a different
and much more used sort:  As pseudo-ttys.  Try running "man pty" on
your computer to learn about them.  These beasts are typically used by
programs like xterm, that need to emulate terminals and all the
signaling capabilities associated with them, such as sending a signal
to the controlled process when the user types ctrl-C, for example.

For example, I type the command "tty" in an xterm, and get the
response /dev/ttyp2 back.  So the shell in that terminal sends its
output to /dev/ttyp2, and receives its input from there.  At the other
end of this pseudo-tty is the master device, which is named
/dev/ptyp2.  The xterm process controls this end.  It passes
keystrokes through it, and gets output from it which it displays on
the screen.  So I could in principle pass "/dev/ttyp2" as an argument
to sb-thread:make-listener-thread and then use this terminal window to
talk to the Lisp, except that the Lisp and my shell would compete for
input from /dev/ttyp2, and chaos would ensue.  I suppose I could run a
command from the shell that does no I/O, such as sleep 86400, but it's
still anybody's guess what ctrl-C would do.

What it all boils down to is this: To do anything useful with this
function, you first need to get hold of an unused pseudo-tty
master/slave pair, then set up a process to control the master device,
perhaps doing some network I/O, and then give the name of the slave
device to sb-thread:make-listener-thread.

Programs I know that do this sort of thing include xterm, ssh (and its
older relatives rsh and telnet), screen, and detachtty.  Highly
specialized programs all.

Maybe you ought to tell us what you want to do, rather than what
function you wish to do it with, and then perhaps someone can help.

- Harald