Instructions to flash an image to an SD card

  1. The first thing you have to do is to fetch the right image for your Raspberry Pi. Please make sure you know which model you have; if you download an image built for a higher family, your board will fail to boot; if you download one built for a lower one, your computer’s performance will be reduced.

    For this example, we will assume you are interested in a Raspberry Pi model 3.

  2. Download the relevant image, either from the daily built images or from the tested images webpages. The downloaded image will have a name matching builddate_raspi_model_release.img.xz, where builddate is the date in CCYYMMDD format the image was generated, model can be 1 (for both 0w and 1), 2, 3 or 4 and release is (currently) either buster or bullseye — In our case resulting in (f.e.), 20210408_raspi_3_bullseye.img.xz.

  3. Download the corresponding sha256 checksum file. This is a much smaller file, only a line of text. So in our case you want 20210408_raspi_3_bullseye.xz.sha256.

  4. Verify both files match:

     $ sha256sum --check 20210408_raspi_3_bullseye.xz.sha256
 20210408_raspi_3_bullseye.xz: OK

    If you get a different result, something is off. Verify your download, or notify us!

  5. Note the corresponding device for your SD card in your computer.

    This is a critical step!
    If you give the wrong device name, you can wipe your computer’s install.
    Please read how to find your SD card’s device if you are not sure.

  6. Now, write the image to your SD card! Make sure you got the right device for the SD card! (you risk losing information otherwise!)
    This has to be done as a privileged user:

     $ xzcat 20210408_raspi_3_bullseye.xz | sudo dd of=/dev/{YOUR_DEVICE} bs=64k oflag=dsync status=progress

    Remember xzcat is decompressing its input; the reported output size will be 1.5GB long, even if your downloaded file is only some hundreds of MB.

  7. That should be it! Wait for the above command to finish (should take no more than a couple of minutes), take your SD card out, put it into your Raspberry, boot and enjoy!

Of course, you will probably be interested on what are your installed defaults and configuration settings.