If you are using a Linux distribution like e.g. Ubuntu, then there are several ways of writing a downloaded image like Debian wheezy on a SD-card.
One possible way is to use dd oder dcfldd.
First you have to check, where your target SD-card is, to ensure you are not killing some important data on one of your harddisks .
Plug your card in and check where it's mounted and umount it:
andreas@Andreas-Ubuntu:~$ mount [...] /dev/sdd1 on /media/andreas/DACE-470F type vfat (rw,nosuid,nodev,uid=1000,gid=1000,shortname=mixed,dmask=0077,utf8=1,showexec,flush,uhelper=udisks2) andreas@Andreas-Ubuntu:~$ sudo umount /media/andreas/DACE-470F
Now you know, where you can find the SD-card, in this case it's at /dev/sdd1. Here we igonore the first partition “1”, because we are overwriting with an image including the partion table, so we focus on /dev/sdd.
Change into the directory, where you find your image, untar or unzip it, so that you finally get the uncompressed image (mine in this example is “2013-09-25-wheezy-raspbian.img”). Now you can use “dd” (which is not returning any output during the write process) or you use “dcfldd”, which is telling a little more during the write process. Remind to install the tools if not already done:
sudo apt-get install dd dcfldd
Finally write the image to SD-card /dev/sdd:
sudo dd if=path_of_your_image.img of=/dev/sdd bs=4M EXAMPLE: sudo dd if=2013-09-25-wheezy-raspbian.img of=/dev/sdd bs=1M
Here nothing is returned, just be patient! If process is finished, your prompt returns.
Or you use dcfldd:
sudo dcfldd if=2013-09-25-wheezy-raspbian.img of=/dev/sdd bs=4M
This command finally returns the following output in my specific example with my 2GB image:
andreas@Andreas-Ubuntu:~/RaspberryPi$ sudo dcfldd if=2013-09-25-wheezy-raspbian.img of=/dev/sdd bs=4M 512 blocks (2048Mb) written. 706+1 records in 706+1 records out andreas@Andreas-Ubuntu:~/RaspberryPi$