mcbe_update.sh

#!/usr/bin/env bash

# Exit if error
set -e
syntax='Usage: mcbe_update.sh SERVER_DIR MINECRAFT_ZIP`'

case $1 in
--help|-h)
	echo "$syntax"
	echo Update Minecraft Bedrock Edition server keeping packs, worlds, JSON files, and PROPERTIES files. Other files will be removed. You can convert a Windows SERVER_DIR to Ubuntu and vice versa if you convert line endings.
	echo
	echo MINECRAFT_ZIP cannot be in SERVER_DIR. Remember to stop server before updating.
	exit
	;;
esac
if [ "$#" -lt 2 ]; then
	>&2 echo Not enough arguments
	>&2 echo "$syntax"
	exit 1
elif [ "$#" -gt 2 ]; then
	>&2 echo Too much arguments
	>&2 echo "$syntax"
	exit 1
fi

server_dir=$(realpath "$1")
new_dir=$server_dir.new
old_dir=$server_dir.old

minecraft_zip=$(realpath "$2")
if [ -n "$(find "$server_dir" -wholename "$minecraft_zip")" ]; then
	>&2 echo MINECRAFT_ZIP cannot be in SERVER_DIR
	exit 1
fi
# Test extracting $minecraft_zip partially quietly
unzip -tq "$minecraft_zip"

echo "Enter Y if you backed up and stopped the server you're updating"
read -r input
input=$(echo "$input" | tr '[:upper:]' '[:lower:]')
if [ "$input" != y ]; then
	>&2 echo "$input != y"
	exit 1
fi

rm -rf "$new_dir"
trap 'rm -rf "$new_dir"; echo fail > "$server_dir/version"' ERR
unzip -q "$minecraft_zip" -d "$new_dir"

cd "$new_dir"
# Trim off $minecraft_zip after last .zip
basename "${minecraft_zip%.zip}" > version
for pack_dir in *_packs; do
	if [ -d "$server_dir/$pack_dir" ]; then
		packs=$(ls "$server_dir/$pack_dir")
		# Escape \ while reading line from $packs
		echo "$packs" | while read -r pack; do
			# Don't clobber 1st party packs
			if [ ! -d "$pack_dir/$pack" ]; then
				cp -r "$server_dir/$pack_dir/$pack" "$pack_dir/"
			fi
		done
	fi
done
for file in worlds *.{json,properties}; do
	if [ -e "$server_dir/$file" ]; then
		cp -r "$server_dir/$file" .
	fi
done

rm -rf "$old_dir"
trap '' SIGTERM
mv "$server_dir" "$old_dir"
mv "$new_dir" "$server_dir"
rm -rf "$old_dir"