A QR Code (it stands for "Quick Response") is a mobile phone readable barcode.simply encode a URL into the QR Code and then point a mobile phone (or other camera-enabled mobile) at it. If the device has had QR Code decoding software installed on it, it will fire up its browser and go straight to that URL.But it doesn't stop there - a QR Code can also contain a phone number, an SMS message VCard data or just plain alphanumeric text, and the will respond by opening up the correct application to handle the encoded data appropriately courtesy of the FNC1 Application Identifiers that are embedded in the encoded data.
The technical specifications for a QR Code are set down in the ISO-18004 standard so they are the same all over the world, and the only significant variations from one QR code to another (apart from the data it contains) is the number of modules required to store the data.
To make things a bit more robust, the QR Code also contains its own error correction data, internal orientation calibration and self-alignment markers. In this way it doesn't matter whether the QR code is upside down or wrapped around a curved surface, the message will still get through.
You can easily generate QR Code under Ubuntu for this you need to install 'qrencode’ package. In Ubuntu, you can install qrencode using this command:
apt-get install qrencodeGo to terminal and type folloing command to generate QR code image:
qrencode -l L -v 1 -o unixlab.png "http://unixlab.blogspot.com"