---

   screen    ( 1 )

---

FLOW-CONTROL

Each window has a flow-control setting that determines how screen
       deals with the XON and XOFF characters (and perhaps the interrupt
       character).  When flow-control is turned off, screen ignores the
       XON and XOFF characters, which allows the user to send them to
       the current program by simply typing them (useful for the emacs
       editor, for instance).  The trade-off is that it will take longer
       for output from a "normal" program to pause in response to an
       XOFF.  With flow-control turned on, XON and XOFF characters are
       used to immediately pause the output of the current window.  You
       can still send these characters to the current program, but you
       must use the appropriate two-character screen commands (typically
       "C-a q" (xon) and "C-a s" (xoff)).  The xon/xoff commands are
       also useful for typing C-s and C-q past a terminal that
       intercepts these characters.

       Each window has an initial flow-control value set with either the
       -f option or the "defflow" .screenrc command. Per default the
       windows are set to automatic flow-switching.  It can then be
       toggled between the three states 'fixed on', 'fixed off' and
       'automatic' interactively with the "flow" command bound to "C-a
       f".

       The automatic flow-switching mode deals with flow control using
       the TIOCPKT mode (like "rlogin" does). If the tty driver does not
       support TIOCPKT, screen tries to find out the right mode based on
       the current setting of the application keypad - when it is
       enabled, flow-control is turned off and visa versa.  Of course,
       you can still manipulate flow-control manually when needed.

       If you're running with flow-control enabled and find that
       pressing the interrupt key (usually C-c) does not interrupt the
       display until another 6-8 lines have scrolled by, try running
       screen with the "interrupt" option (add the "interrupt" flag to
       the "flow" command in your .screenrc, or use the -i command-line
       option).  This causes the output that screen has accumulated from
       the interrupted program to be flushed.  One disadvantage is that
       the virtual terminal's memory contains the non-flushed version of
       the output, which in rare cases can cause minor inaccuracies in
       the output.  For example, if you switch screens and return, or
       update the screen with "C-a l" you would see the version of the
       output you would have gotten without "interrupt" being on.  Also,
       you might need to turn off flow-control (or use auto-flow mode to
       turn it off automatically) when running a program that expects
       you to type the interrupt character as input, as it is possible
       to interrupt the output of the virtual terminal to your physical
       terminal when flow-control is enabled.  If this happens, a simple
       refresh of the screen with "C-a l" will restore it.  Give each
       mode a try, and use whichever mode you find more comfortable.