First of all, download Raspbian. Check the website for the latest version. In my case I used wget to download the version:
wget http://126.96.36.199/bt/29aa44acfa3a7a78dd438e9e91dd3142247817fd/data/2014-09-09- wheezy-raspbian.zip
Get the checksum to check if the download was correct:
Unpack the zip archive:
Check all block devices with the following command, before you put the SD card into your PC:
Unmount the partition:
sudo umount /dev/
Copy the img file to the SD card – Be careful not to overwrite your HDD.
sudo dd if=2014-09-09-wheezy-raspbian.img of=/dev/ bs=4k
You’re finished. Put the SD card into the Pi and turn it on.