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xvncviewer - a X viewer client for Virtual Network Computing
xvncviewer [options] [host:display]
xvncviewer [options] -listen
[display]
options are [-shared] [-viewonly] [-fullscreen] [-passwd file] [-encodings encoding-names]
[-bgr233] [-owncmap] [-truecolour] [-depth num] [-display display] [-geometry geom]
[-help]
xvncviewer is a X viewer client for Xvnc, the free X
server for Virtual Network Computing (VNC). It can connect to a running
Xvnc server and display it in a X window. Further it can transmit mouse
and keyevents to the server.
There are viewers for a variety of other plattforms,
e.g. SVGAlib and Windows. For Linux and Windows also a server exists. With
the built-in Java classes, you can even use a Java capable Internet browser
to connect to Xvnc.
- xvncviewer localhost:1
- Connects to a running
Xvnc session on the local workstation and displays its content in a X window.
- xvncviewer -display :0 flora:1
- Connects to a running Xvnc on host flora and
displays its content in a X window of display :0 at localhost.
- -help
- Prints a short usage notice to stderr.
- -shared
- When you make a connection
to a VNC server, all other existing connections are normally closed. This
option requests that they be left open, allowing you to share the desktop
with someone already using it.
- -viewonly
- This option disables transfer of
mouse and key events from the client to the server. This does not automatically
imply -shared.
- -fullscreen
- Start in fullscreen mode.
- -passwd file
- If you are
on a filesystem which gives you access to the password file used by the
server, you can specify it here to avoid typing it in.
- -encodings encoding-names
- VNC provides several different compression encodings; this option specifies
a set of them in order of preference. Encodings are specified separated
with spaces, and must thus be enclosed in quotes if more than one is specified.
Available encodings, in default order for a remote connection, are copyrect,
hextile, corre, rre, and raw. For a local connection (to the same machine),
the default order to try is raw, copyrect, hextile, corre, and rre.
- -bgr233
- Tells the VNC server to send pixels 8-bits deep. This reduces network traffic,
but increases CPU utilization on servers deeper than 8 bits due to the
translation required. Additionally, the colors are sometimes wrong. The
bgr233 format is an 8-bit "true color" format, with 2 bits blue, 3 bits
green, and 3 bits red. This is also the format used by the Java client.
- -owncmap
- This makes the viewer to install a private colormap on displays
with a color depth of 8 bits.
- -truecolour
- Attempt to use a truecolour visual.
(Americans should note the spelling of "colour".)
- -depth
- On an X-server which
supports multiple true-color depths, attempt to use the specified one; if
successful, this is the depth which will be requested from the VNC server.
To force a particular depth from the vnc server, see the -bgr233 option.
- -listen
- This causes the viewer to listen on port 5500+displaynumber for
reverse connections from a server. WinVNC supports reverse connections
using the "Add New Client" menu option, or the -connect command line option.
Standard Xt Options - xvncviewer accepts the usual options; see X(3x)
for
more information. A few extremely common options are listed below.
- -display num
- This allows you to specify the X display on which the VNCviewer window
should appear.
- -geometry geometry-string
- This specifies the initial size and
location of the viewer window.
- -compresslevel
- Specifies the compression level
to use (TightVNC).
- -quality
- Set the quality of the output (TightVNC).
- -nocursorshape
- Do not show the cursor from the workspace (TightVNC).
- -noshared
- Disallow
sharing of the workspace.
- -tunnel
-
The server supplies information
in whatever format is desired by the client, in order to make the client
as easy as possible to implement. If the client represents itself as able
to use multiple formats, the server will choose one.
Pixel format refers
to the representation of an individual pixel. The most common formats are
24 and 16 bit "true-color" values, and 8-bit "color map" representations,
where an arbitrary map converts the color number to RGB values.
Encoding
refers to how a rectangle of pixels are sent (all information in VNC is
sent as rectangles). All rectangles come with a header giving the location
and size of the rectangle and an encoding type used by the data which follows.
These types are listed below.
- raw
- The raw encoding simply sends width*height
pixel values. All clients are required to support this encoding type. Raw
is also the fastest when the server and viewer are on the same machine,
as the connection speed is essentially infinite and raw encoding minimizes
processing time.
- copyrect
- The Copy Rectangle encoding is efficient when
something is being moved; the only data sent is the location of a rectangle
from which data should be copied to the current location. Copyrect could
also be used to efficiently transmit a repeated pattern.
- RRE
- The Rise-and-Run-length-Encoding
is basically a 2D version of run-length encoding (RLE). In this encoding,
a sequence of identical pixels are compressed to a single value and repeat
count. In VNC, this is implemented with a background color, and then specifications
of an arbitrary number of subrectangles and color for each. This is an
efficient encoding for large blocks of constant color.
- CoRRE
- This is a minor
variation on RRE, using a maximum of 255x255 pixel rectangles. This allows
for single-byte values to be used, reducing packet size. This is in general
more efficient, because the savings from sending 1-byte values generally
outweighs the losses from the (relatively rare) cases where very large
regions are painted the same color.
- Hextile
- Here, rectangles are split up
in to 16x16 tiles, which are sent in a predetermined order. The data within
the tiles is sent either raw or as a variant on RRE.
- Other
- Additional encodings,
such as zlib, have been written, but are not a stock part of VNC. See http://www.uk.research.att.com/vnc/extras.html#zlib
for more information.
- /usr/bin/vncpasswd
- Command to create and change
password files to be used by the RFB protocol (can be specified with the
-passwd option).
- /usr/bin/vncserver
- A wrapper script around Xvnc to start
the server with appropriate defaults.
- /usr/bin/Xvnc
- The real server. Will
be invoked by vncserver.
svncviewer(1)
, vncpasswd(1x)
, vncserver(1x)
,
Xvnc(1x)
, vnc.conf(5)
.
http://www.uk.research.att.com/vnc/xvncviewer.html
http://www.uk.research.att.com/vnc/protocol.html
VNC developed at Olivetti
Research Labs, Cambridge (now AT&T Laboratories, Cambridge) by Tristan Richardson,
Ken Wood, James Weatherall, Andy Harter, Charlie McLachlan, Paul Webster,
Quentin Stafford-Fraser and others. This manpage written by Marcus Brinkmann
for the Debian GNU/Linux distribution.
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