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.TH Xephyr 1 "xorg-server 1.20.11" "X Version 11"
.SH NAME
Xephyr - X server outputting to a window on a pre-existing X display
.SH SYNOPSIS
.B Xephyr
.RI [\fB:\fP display ]
.RI [ option
.IR ... ]
.SH DESCRIPTION
.B Xephyr
is a kdrive server that outputs to a window on a pre-existing "host"
X display.
Think
.I Xnest
but with support for modern extensions like composite, damage and randr.
.PP
Unlike
.I Xnest
which is an X proxy, i.e.  limited to the capabilities of the host X server,
.B Xephyr
is a real X server which
uses the host X server window as "framebuffer" via fast SHM XImages.
.PP
It also has support for "visually" debugging what the server is
painting.
.SH OPTIONS
The server accepts all the standard options of Xserver(1)
and the following additional options:
.TP 8
.BI -screen " width" x height
sets the screen size.
.TP 8
.BI -parent " id"
uses existing window
.I id .
If a
.BI -screen
argument follows a
.BI -parent
argument, this screen is embedded into the given window.
.TP 8
.B -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.
.TP 8
.B -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.
.TP 8
.B -no-host-grab
Disable grabbing the keyboard and mouse.
.SH "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.
.SH CAVEATS
.PP
.IP \(bu 2
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.
.IP \(bu 2
The '-host-cursor' cursor is static in its appearance.
.IP \(bu 2
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.
.IP \(bu 2
Keyboard handling is basic but works.
.IP \(bu 2
Mouse button 5 probably won't work.
.SH "SEE ALSO"
X(7), Xserver(1)
.SH AUTHOR
Matthew Allum <mallum@o-hand.com> 2004