NAME

       Xephyr - X server outputting to a window on a pre-existing X display

SYNOPSIS

       Xephyr [:display] [option ...]

DESCRIPTION

       Xephyr  is  a  kdrive  server that outputs to a window on a pre-existing "host" X display.
       Think Xnest but with support for modern extensions like composite, damage and randr.

       Unlike Xnest which is an X proxy, i.e.  limited to the capabilities of the host X  server,
       Xephyr  is  a  real X server which uses the host X server window as "framebuffer" via fast
       SHM XImages.

       It also has support for "visually" debugging what the server is painting.

OPTIONS

       The server accepts all the standard options of Xserver(1)  and  the  following  additional
       options:

       -screen widthxheight
               sets the screen size.

       -parent id
               uses  existing window id .  If a -screen argument follows a -parent argument, this
               screen is embedded into the given window.

       -host-cursor
               set 'cursor acceleration': The host's cursor is reused. This is only really  there
               to aid debugging by avoiding server paints for the cursor. Performance improvement
               is negligible.

       -resizeable
               Allow the Xephyr window to be resized, even if not embedded into a parent  window.
               By default, the Xephyr window has a fixed size.

       -no-host-grab
               Disable grabbing the keyboard and mouse.

SIGNALS

       Send  a  SIGUSR1 to the server (e.g. pkill -USR1 Xephyr) to toggle the debugging mode.  In
       this mode red rectangles are painted to screen areas getting painted before  painting  the
       actual  content.   The delay between this can be altered by setting a XEPHYR_PAUSE env var
       to a value in micro seconds.

CAVEATS

       • Rotated displays are currently updated via full blits. This  is  slower  than  a  normal
         orientated display. Debug mode will therefore not be of much use rotated.

       • The '-host-cursor' cursor is static in its appearance.

       • The  build  gets  a  warning about 'nanosleep'. I think the various '-D' build flags are
         causing this. I haven't figured as yet how to work round it. It doesn't appear to  break
         anything however.

       • Keyboard handling is basic but works.

       • Mouse button 5 probably won't work.

SEE ALSO

       X(7), Xserver(1)

AUTHOR

       Matthew Allum <mallum@o-hand.com> 2004