Installing Raspbian on SD Cards

2019-06-22T00:00:00+00:00

Recently I have started dabbling with Raspberry Pi Single Board Computers (SBCs). One of the first tasks encountered when setting up a new Raspberry Pi is getting the Raspbian operating system loaded onto a SD card that the computer will boot from. This involves copying the operating system to the card and, commonly, configuring WiFi and SSH so that the Pi is accessible after it boots up. Several articles out on the internet cover various aspects of this process, but I couldn’t find one that gathered everything into one place, so I decided to write the process down.

Step 1: Install Raspbian on the card

The first step is to download a Raspbian disk image and copy it to the SD card. The latest images can be found at:

https://www.raspberrypi.org/downloads/raspbian/

The instructions in this article will work with both the “desktop” and “lite” versions of the distribution. When the download has completed, extract the archive to get a .img file. This image can be written to a SD card using the dd utility:

sudo dd bs=1m conv=sync \
  if=2019-04-08-raspbian-stretch-lite.img \
  of=«path to SD card device»

This process will completely overwrite the SD card with the content of the disk image which is usually:

A /boot partition which uses the FAT32 filesystem. This contains the bootloader code for Raspberry Pi hardware and is also where configuration files can be created in order to ensure the computer starts with systems like WiFi and SSH configured.
A / partition which uses the EXT4 filesystem. This contains the Linux operating system which is launched by the /boot partition as part of startup.

Step 2: Configure WiFi and SSH

Once the .img file has been copied to the SD card, WiFi and SSH can be configured by mounting the /boot partition and writing configuration files to it. The remainder of this section will assume the partition has been mounted to /Volumes/boot. Substitute another path, such as /mnt/boot, as appropriate.

Configuring WiFi

The Pi can be configured to connect to a WiFi network when it boots by adding a wpa_supplicant.conf file to the /boot partition:

cat <<'EOF' > /Volumes/boot/wpa_supplicant.conf
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=«your_ISO-3166-1_two-letter_country_code»

network={
    ssid="«your WiFi network name»"
    psk="«your WiFi password»"
    key_mgmt=WPA-PSK
}
EOF

The ISO country code is required to ensure the WiFi transmitter is configured properly. A list of current codes can be found here:

https://www.iso.org/obp/ui/#search/code/

Configuring SSH

By default, Raspbian will not start the ssh service. This can be changed by adding an empty file named ssh to the /boot partition:

touch /Volumes/boot/ssh

This will allow SSH access with Raspbian’s default username/password of pi/raspberry. If the Pi is connected to a network where it will be exposed to other users or the internet-at-large, then you must connect immediately after boot and use sudo raspi-config to change the password. This will prevent a hostile takeover of the computer as the pi user has access to the root account via the sudo command and the default raspberry password is well-known to other technical users and the internet-at-large.

References