Here are a few setup tips if you're running into issues firing up a Minecraft Bedrock server on Ubuntu Linux.
First of all, you'll want to download the server software from https://minecraft.net/en-us/download/server/bedrock/. It will come in ZIP format and you can uncompress it and move it to your Linux server however you like.
The first issue that you'll likely run into after trying to execute LD_LIBRARY_PATH=. ./bedrock_server is a permission denied error. This is because the "bedrock_server" script hasn't been setup to execute.
-bash: ./bedrock_server: Permission denied
chmod +x ./bedrock_server
The next issue that you're likely to run into is that as soon as you leave the terminal your server shuts down. Further, if you try to run it in the background with & at the end of your command the server starts up but never gets to the point where it accepts incoming connections. To get around this the easiest thing to do is to use the "screen" program which will allow you to start the server and then end your terminal session leaving it running.
sudo apt-get update sudo apt-get install screen
Now that screen has been installed you can invoke it by entering screen. This will seemingly leave you at a bash prompt. The difference is, when you start the bedrock server with LD_LIBRARY_PATH=. ./bedrock_server you can then leave your terminal session and it will continue running which is what most people want.
The console for the bedrock server allows you to enter some commands that you might need, like setting up operators with "op". In order to get back to the screen that's running your server you can invoke screen -ls and then use screen -r *name of the screen* to re-attach to it.
x@mc-server:~$ screen -ls
There is a screen on:
2885.pts-0.mc-server (01/05/2019 06:35:59 PM) (Detached)
1 Socket in /run/screen/S-pi.
x@mc-server:~$ screen -r pts-0.mc-server
In the above I got a listing of the screens then used screen -r pts-0.mc-server to reconnect to that screen. If you only have one screen it will match the prefix so screen -r pts would have also worked in my case.