pa28/headless_pi

Headless Pi

A shell script to configure an SDCard for a headless after imaging but before first boot.

If you play around with Raspberry Pi computers long enough you will get to the point when you have more than one Pi on a network and one of them headless. In these cases it is helpful to set up an number of things on a new headless Pi before first boot.

Prerequisites

You will need, of course, a Pi, an SDCard, a machine to image the SDCard on and the big one for many of the things this script does, a Linux/Unix system to mount the SDCard on to run the script (which can also be the machine you image the SDCard on). This is because the Pi root filesystem is EXT3. If you really must use Windows there are programs you can you can use to access the root filesystem. This is beyond the scope of the project. You can use a Raspberry Pi for imaging and running the script if you have the equipment to mount an SDCard by USB.

Limitations

All the changes to the root file system require super user privileges so if doing more tha setting up SSH and WiFi you will need to run headless from sudo, and of course have those privileges on the system. This does not change the identity of the user running the script as far as headless is concerned.

The script is designed to be run on a fresh Raspberry Pi OS image. Re-running the script on an image may misconfigure the system. This is especially true of changes to the root filesystem and when the configuration file has been changed.

What Does it Do?

The script uses a configuration file, which will be discussed later, these are the things that the script will do for you with proper configuration:

• Enable the SSH Daemon;
• Configure WiFi (if provided the correct config file);
• Change the hostname;
• Change the user name from pi to something else;
• Extract a tar file to the user home directory, inteded to set up SSH credentials;
• Copy the id_rsa.pub from the user running the script to the Pi user .ssh/authorized_keys file and the root .ssh/authorized_keys file;
• Install my Debian repository on the system;
• Change the Pi system time zone.

What Will it Do?

What it will do depends on the content of the configuration file. Each Pi that you are managing with the script should have its own configuration file. Here is a sample configuration (the mypi file included):

#
# Configuration for mypi host
#
PI_HOSTNAME="mypi"
PI_USERNAME="notpi"

# Configure SSH Daemon
SSHD="yes"

# Configure WIFI from file
WIFI="wpa_supplicant.conf"

# Add current user ~/.ssh/id_rsa.pub to authorized_keys for PI_USERNAME and root.
AUTH_KEYS="yes"

# Add VE3YSH Repository to system.
AUTH_REPO="yes"

# Set the system time zone see /usr/share/zoneinfo
PI_TIME_ZONE="America/Toronto"

SSHD

If set to yes the SSH Daemon will be enabled by creating a file called ssh in the boot partition.

WIFI

If set to the name of the file that resides in the same directory as the headless script the file will be copied to wpa_supplicant.conf in the boot partition. The format is not checked. Assuming you have provided a well formed and correct wpa_supplicant.conf file this will enable the Pi to connect to a WiFi network.

PI_HOSTNAME

If defined to a non-empty value, the value will be used as the hostname by writing it in /etc/hostname and /etc/hosts on the rootfs partition.

PI_USERNAME

Controls how the user configuration. If defined to a non-empty value that is not pi all of the user configuration changes will be made if other conditions are met:

• Change the user name from pi to something else;
• Extract a tar file to the user home directory, inteded to set up SSH credentials;
• Copy the id_rsa.pub from the user running the script to the Pi user .ssh/authorized_keys file and the root .ssh/authorized_keys file.

Other Conditions

The tar file to be created must reside in the same directory as the headless script and must have a name made up of the configuration file name (in this case mypi) and the PI_USERNAME (in this case notpi):

mypi_notpi.ssh.tgz

To copy id_rsa.pub as described the AUTH_KEYS variable must be set to yes, and the id_rsa.pub file must exist the the home directory of the account running the script.

And as previously mentioned if PI_USERNAME is set to pi the user name is not changed.

AUTH_REPO

If set to yes a sources list file will be created directing the configured Pi to look to my Debian repository for packages and their updates:

deb [trusted=yes] https://apt.fury.io/ve3ysh/ /

PI_TIME_ZONE

If set to a non-empty value will change the link on the configured Pi /etc/localtime to the specified time zone. The value must specify a directory path that exists under /usr/share/zoneinfo on a RaspberryPi or similar system.