Arch Linux User Repository

To get an overview of the available options provided by the management script, be sure to have a look at the help page or read the according section on the ArchWiki article [1].

You can quit the console without shutting down the server by press ctrl+a d (first ctrl+a and after releasing the buttons press d; ctrl+b also works). This will detach your input from the server console. The attaching and detaching is done with tmux (previously GNU screen) since it lets you view and type into the console, send single commands to it and keep it alive without a connected user. Take a look at the the command overview at the ArchWiki [2] to get a feel for its power. (@carmelo12341)

[1] https://wiki.archlinux.org/title/Minecraft#Setup [2] https://wiki.archlinux.org/title/Tmux

edit: I fixed it by installing the latest openjdk (jre-openjdk-headless) version and setting it as the default: sudo archlinux-java set java-16-openjdk

The version that no longer works is jre8-openjdk-headless.

@edh, unfortunately running these commands made no change. The output was:

[user@host minecraft-server-old]$ sudo -u minecraft screen -S minecraft -rx
[sudo] password for user: 
There is no screen to be attached matching minecraft.

The same for idle_server_minecraft. BTW you should update the pinned comment too.

edit: I believe the issue is related to Java:

Exception in thread "main" java.lang.UnsupportedClassVersionError: net/minecraft/server/Main has been compiled by a more recent version of the Java Runtime (class file version 60.0), this version of the Java Runtime only recognizes class file versions up to 52.0

Version 60 = Java 16

@InFerNo

Very good point! I forgot to include the install file in the PKGBUILD :(

The message should have been:

The management script switched from GNU screen to tmux.
Manual intervention is needed to close the previous GNU screen sessions:
Use `sudo -u minecraft screen -S minecraft -rx` to attach to the minecraft session and stop it.
Do the same for the `idle_server_minecraft` session if one is running.

@edh

edit: here is my output, I see no instructions:

https://pastebin.com/LegNUqrH

@InFerNo The management script switched from GNU screen to tmux in the meantime. Did you follow the instructions that were printed after the upgrade?

I keep getting minecraftd[133901]: The corresponding tmux session for minecraft was already dead. How can I fix this? I upgraded from 1.16.5.

If you would like to use minecraftd console without entering your password to both enter and exit the console you need to add a line to your /etc/sudoers file.

<user> ALL=(minecraft) NOPASSWD: ALL

You should understand the potential security issues here. This will allow <user> to run any command on your system as the minecraft user. If the user only has permission on the file system for files related to the minecraft server this is probably fine.

@auricom sudo is needed by the minecraft server management script to run everything as the minecraft user. While one could replace sudo calls with simple su ones, using sudo allows the user to configure rules for who can control the minecraft server on a system.

EDIT: Using the sticky bit and doing the permission handling oneself is disallowed by the kernel for good reasons for all interpreted executables.

Is the Sudo dependency really necessary or could it be removed? A program calling sudo directly is dumb.

@Refutationalist Sorry if my question was phrased poorly. I was specifically asking about objective arguments in favor of GNU screen, i.e. why a new user should prefer GNU screen over tmux for a minecraft server management script.

The severe bug I mentioned was brought up in this comment section by Xarius on 2021-02-11 17:49 in https://aur.archlinux.org/packages/minecraft-server/?O=20&PP=10#comment-791132 . It is tracked under CVE-2021-26937 .

Tmux has a more active community and using it in scripts feels way more natural. Thus, while in theory they both do roughly the same thing, tmux feels much more flexible to me. Actually I long toyed with the idea of rewriting every GNU screen call to a tmux call myself (see https://aur.archlinux.org/packages/minecraft-server/?O=20&PP=10#comment-791132 ) but have not had the time to do so just yet.

@Static_Rocket Would you be willing to submit a merge request on github for this (https://github.com/Edenhofer/abs/blob/master/minecraft-server/minecraftd.sh)? I would be more than happy to help with any remaining issues.

@Refutationalist For starters, this bug and it's workaround are documented explicitly in minecraftd.sh , but I'm not sure if it's still an issue. https://serverfault.com/questions/116775/sudo-as-different-user-and-running-screen