dietpi-activate-overlay

#!/bin/bash

# DietPi device tree overlay activation program
# used to setup existing overlays in /boot/dtb/<chip>/overlay/
#
# based upon armbian-add-overlay

# Copyright (c) 2017 The Armbian Project https://www.armbian.com/
#
# This file is licensed under the terms of the GNU General Public
# License version 2. This program is licensed "as is" without any
# warranty of any kind, whether express or implied.

if [[ ! -n $1 ]]; then
	echo >&2 "Usage: $0 <overlay_name>"
	exit -1
fi

if [[ $EUID -ne 0 ]]; then
	echo >&2 "This program must be run with superuser rights"
	exit -1
fi

if [[ ! -f /boot/dietpiEnv.txt ]]; then
	echo >&2 "DietPi is not installed properly. Missing dietpiEnv.txt"
	exit -1
fi

if ! grep -q '^setenv overlay_error' /boot/boot.cmd; then
	echo >&2 "Overlays are not supported on ${LINUXFAMILY^} based boards."
	exit -1
fi

overlay=$1

if grep -q '^overlays=' /boot/dietpiEnv.txt; then
	line=$(grep '^overlays=' /boot/dietpiEnv.txt | cut -d'=' -f2)
	if grep -qE "(^|[[:space:]])${overlay}([[:space:]]|$)" <<< $line; then
		echo "Overlay ${overlay} was already added to /boot/dietpiEnv.txt, skipping"
		exit 0
	elif grep -q '^overlays=\s*$' /boot/dietpiEnv.txt; then
		sed -i -e "s/^overlays=\s*$/overlays=${overlay}/" /boot/dietpiEnv.txt
	else
		sed -i -e "/^overlays=/ s/$/ ${overlay}/" /boot/dietpiEnv.txt
	fi
else
	sed -i -e "\$aoverlays=${overlay}" /boot/dietpiEnv.txt
fi

echo "Reboot is required to apply the changes"