add --listen docs

* doc/ref/scheme-scripts.texi (Invoking Guile): Add --listen
  documentation.

diff --git a/doc/ref/scheme-scripts.texi b/doc/ref/scheme-scripts.texi
index 8d47746..5a151a4 100644 (file)
--- a/doc/ref/scheme-scripts.texi
+++ b/doc/ref/scheme-scripts.texi
@@ -189,6 +189,28 @@ interactive session.  When executing a script with @code{-s} or
 Do not use the debugging VM engine, even when entering an interactive
 session.
 
+@item --listen[=@var{p}]
+While this program runs, listen on a local port or a path for REPL
+clients.  If @var{p} starts with a number, it is assumed to be a local
+port on which to listen.  If it starts with a forward slash, it is
+assumed to be a path to a UNIX domain socket on which to listen.
+
+If @var{p} is not given, the default is local port 37146.  If you look
+at it upside down, it almost spells ``Guile''.  If you have netcat
+installed, you should be able to @kbd{nc localhost 37146} and get a
+Guile prompt.  Alternately you can fire up Emacs and connect to the
+procedure; see @ref{Using Guile in Emacs} for more details.
+
+Note that opening a port allows anyone who can connect to that port---in
+the TCP case, any local user---to do anything Guile can do, as the user
+that the Guile process is running as.  Don't use @option{--listen} on
+multi-user machines.  Of course, if there is no @option{--listen}
+argument, no port will be opened.
+
+That said, @code{--listen} is great for interactive debugging and
+development.
+
+@vnew{2.0}
 @item -h@r{, }--help
 Display help on invoking Guile, and then exit.