entry.sh

#!/bin/bash

# Send SIGTERM to child processes of PID 1.
function signal_handler()
{
	kill $pid
}

function update_hostname()
{
	HOSTNAME="$HOSTNAME-${RESIN_DEVICE_UUID:0:7}"
	echo $HOSTNAME > /etc/hostname
	echo "127.0.1.1 $HOSTNAME" >> /etc/hosts
	hostname "$HOSTNAME"
}

function mount_dev()
{
	mkdir -p /tmp
	mount -t devtmpfs none /tmp
	mkdir -p /tmp/shm
	mount --move /dev/shm /tmp/shm
	mkdir -p /tmp/mqueue
	mount --move /dev/mqueue /tmp/mqueue
	mkdir -p /tmp/pts
	mount --move /dev/pts /tmp/pts
	touch /tmp/console
	mount --move /dev/console /tmp/console
	umount /dev || true
	mount --move /tmp /dev

	# Since the devpts is mounted with -o newinstance by Docker, we need to make
	# /dev/ptmx point to its ptmx.
	# ref: https://www.kernel.org/doc/Documentation/filesystems/devpts.txt
	ln -sf /dev/pts/ptmx /dev/ptmx
	mount -t debugfs nodev /sys/kernel/debug
}

function init_systemd()
{
	GREEN='\033[0;32m'
	echo -e "${GREEN}Systemd init system enabled."
	env > /etc/docker.env

	printf '#!/bin/bash\n exec ' > /etc/resinApp.sh
	printf '%q ' "$@" >> /etc/resinApp.sh
	chmod +x /etc/resinApp.sh

	mkdir -p /etc/systemd/system/launch.service.d
	cat <<-EOF > /etc/systemd/system/launch.service.d/override.conf
		[Service]
		WorkingDirectory=$(pwd)
	EOF

	exec /sbin/init quiet systemd.show_status=0
}

function init_non_systemd()
{
	# trap the stop signal then send SIGTERM to user processes
	trap signal_handler SIGRTMIN+3 SIGTERM

	udevd & 
	udevadm trigger &> /dev/null
	
	CMD=$(which "$1")
	# echo error message, when executable file doesn't exist.
	if [ $? == '0' ]; then
		shift
		"$CMD" "$@" &
		pid=$!
		wait $pid
	else
		echo "Command not found: $1"
		exit 1
	fi
}

if [ ! -z "$RESIN_SUPERVISOR_API_KEY" ] && [ ! -z "$RESIN_DEVICE_UUID" ]; then
	# run this on resin device only
	update_hostname
	mount_dev
fi 

if [ "$INITSYSTEM" = "on" ]; then
	init_systemd "$@"
else
	init_non_systemd "$@"
fi