Installing DRBL CloneZilla Server in Ubuntu 12.04

First thing you will do is open your terminal, press Ctrl+Alt+T and then type
wget -q http://drbl.org/GPG-KEY-DRBL -O- | sudo apt-key add -

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Input password and type sudo gedit /etc/apt/sources.list

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Paste to your source list the following and then save.
deb http://archive.ubuntu.com/ubuntu precise main restricted universe multiverse
deb http://drbl.sourceforge.net/drbl-core drbl stable

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In your terminal again, type sudo apt-get update

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After the update is done type sudo apt-get install drbl hit enter and you are done with the installation of DRBL

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Reference: Installing DRBL, Ubuntu 12.04 64 bit