Document control mode in the manpage, from George Nachman.

tmux.1

@@ -23,7 +23,7 @@
 .Sh SYNOPSIS
 .Nm tmux
 .Bk -words
-.Op Fl 28lquvV
+.Op Fl 28lCquvV
 .Op Fl c Ar shell-command
 .Op Fl f Ar file
 .Op Fl L Ar socket-name
@@ -102,6 +102,11 @@ to assume the terminal supports 256 colours.
 Like
 .Fl 2 ,
 but indicates that the terminal supports 88 colours.
+.It Fl C
+Start in control mode.
+Given twice
+.Xo ( Fl CC ) Xc
+disables echo.
 .It Fl c Ar shell-command
 Execute
 .Ar shell-command
@@ -3610,6 +3615,94 @@ option above and the
 .Xr xterm 1
 man page.
 .El
+.Sh CONTROL MODE
+.Nm
+offers a textual interface called
+.Em control mode .
+This allows applications to communicate with
+.Nm
+using a simple text-only protocol.
+.Pp
+In control mode, a client sends
+.Nm
+commands or command sequences terminated by newlines on standard input.
+Each command will produce one block of output on standard output.
+An output block consists of a
+.Em %begin
+line followed by the output (which may be empty).
+The output block ends with a
+.Em %end
+or
+.Em %error .
+.Em %begin
+and matching
+.Em %end
+or
+.Em %error
+have two arguments: an integer time (as seconds from epoch) and command number.
+For example:
+.Bd -literal -offset indent
+%begin 1363006971 2
+0: ksh* (1 panes) [80x24] [layout b25f,80x24,0,0,2] @2 (active)
+%end 1363006971 2
+.Ed
+.Pp
+In control mode,
+.Nm
+outputs notifications.
+A notification will never occur inside an output block.
+.Pp
+The following notifications are defined:
+.Pp
+.Bl -tag -width Ds
+.It Ic %exit Op Ar reason
+The
+.Nm
+client is exiting immediately, either because it is not attached to any session
+or an error occurred.
+If present,
+.Ar reason
+describes why the client exited.
+.It Ic %layout-change Ar window-id Ar window-layout
+The layout of a window with ID
+.Ar window-id
+changed.
+The new layout is
+.Ar window-layout .
+.It Ic %output Ar source-pane Ar value
+A window pane,
+.Ar source-pane ,
+produced output.
+.Ar value
+contains that output with each byte encoded as two hex digits.
+.It Ic %session-changed Ar session-id Ar name
+The client is now attached to the session with ID
+.Ar session-id ,
+which is named
+.Ar name .
+.It Ic %session-renamed Ar name
+The current session was renamed to
+.Ar name .
+.It Ic %sessions-changed
+A session was created or destroyed.
+.It Ic %unlinked-window-add Ar window-id
+The window with ID
+.Ar window-id
+was created but is not linked to the current session.
+.It Ic %window-add Ar window-id
+The window with ID
+.Ar window-id
+was linked to the current session.
+.It Ic %window-close Ar window-id
+The window with ID
+.Ar window-id
+closed.
+.It Ic %window-renamed Ar window-id Ar name
+The window with ID
+.Ar window-id
+was renamed to
+.Ar name .
+.El
 .Sh FILES
 .Bl -tag -width "/etc/tmux.confXXX" -compact
 .It Pa ~/.tmux.conf