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A command line VNC client and python library
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vncdotool is a command line VNC client.

It comes in handy when automating interactions with virtual machines or some hardware devices that are otherwise difficult to control.

Currently under development, so use at your own peril but what is the worst that could happen?

Quick Start

To see vncdotool in action you can run it against an existing VNC server or start one locally with x11vnc. Then you can run:

pip install twisted # if you don't already have it
python vncdotool/ -s hostaddr type "hello world"

If you have PIL installed then you can do a screen captures with:

python vncdotool/ -s hostaddr capture screen.png


vncdotool depends on Twisted. Additionally, for capture and expect commands to work you will need the Python Image Library. You can use your favourite package manager to grab them. Once you have the dependencies installed you install from the unpacked source tree.

python install


Once installed you can use the vncdotool command to send key-presses. Alphanumerics are straightforward just specify the character. For other keys longer names are used:

> vncdotool key a
> vncdotool key 5
> vncdotool key .
> vncdotool key enter
> vncdotool key shift-a
> vncdotool key ctrl-C
> vncdotool key ctrl-alt-del

To type longer strings when entering data or commands you can use the type c command, which does not support special characters:

> vncdotool type "hello world"

You can control the mouse pointer with move and click commands. NOTE, you should almost always issue a move before a click, as in:

> vncdotool move 100 100 click 1

Whereas, the following would seem to be equivalent but would actually click at -8, 0. This behaviour is due to how click events are sent:

> vncdotool move 100 100
> vncdotool click 1

If you have the Python Imaging Library (PIL) installed you can also make screen captures of the session:

> vncdotool capture screenshot.png

With PIL installed, you can wait for the screen to match a known image.:

> vncdotool expect somescreen.png 0

Putting it all together you can specify multiple actions on a single command line. You could automate a login with the following:

> vncdotool type username key enter expect password_prompt.png
> vncdotool type password move 100 150 click 1 expect welcome_screen.png

For more complex automation you can read commands from stdin or a file. The file format is simply a collection of actions:

> echo "type hello" | vncdotool -

> cat some_file.vdo
# select the name text box, enter your name and submit
move 100 100 click 1 type "my name" key tab key enter

# grab the result
capture screenshot.png

> vncdotool some_file.vdo

Creating long lists of commands can be time consuming so vncdotool provides a record mode that logs messages and screen captures. As the log is a text file you can edit it to tweak the behaviour.:

> vncdotool record 6000 vnc.vdo
> vncviewer localhost:6000
> sed -i s/click 1/click 2/ vnc.vdo
> vncdotool vnc.vdo

For convience you can launch a VNCViewer connected to a vncdotool in record mode with:

> vncdotool viewer somefile.vdo

By running in service mode vncdotool will create a new file for every client connection and record each clients activity. This can be useful for quickly recording a number of testcases.:

> vncdotool service 6000
> vncviewer localhost:6000
> vncviewer localhost:6000


Comments, suggestions and patches are welcome and appreciated. They can be sent to or via


Thanks to Chris Liechti, techtonik and Todd Whiteman for developing the RFB and DES implementations used by vncdotool.

_python-vnc-viewer: _Twisted: _PIL:

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