Other articles

1. iptables FAQ

   List rules

   iptables -L -v -n --line-numers
   

   We can use the line numbers later to delete rules.

   Delete rules

   iptables -D INPUT 1
   

   INPUT is the chain from which we delete the rule with line number 1

   Allow incoming connection to a port

   Allow incoming connections to port 1510 on …

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2. How to create a systemd service?

   Running process

   We will use a Minecraft server as an example. This is a Java application. It should start when the machine boots up and it stops gracefully when the service is stopped. The service name will be minecraft.

   Create a text file at the following location: /etc/systemd/system …

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3. Backup and restore your Linux system disk

   Backup your system disk when its not active

   Boot-up another system with your system disk attached. Mount it and backup all system files:

   mount ${srcdev} /mnt
   cd /mnt
   tar --exclude sys.tar.bz2 -czpf sys.tar.bz2 ./
   umount /mnt
   

   -z - infer the compression format from the extension

   -p - save all …

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4. Build Qt Statically

   This article is a list of steps to build Qt statically on Windows so that you can build your applications as a single self-contained binary. The environment for building is MINGW 32

   Downloads

   Before you start you need to download the following files. This link is a good place to …

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5. Build AppImageKit

   This article is a manual to build AppImageKit from source

   Install dependencies

   apt install zsync libglib2.0-dev desktop-file-utils libtool automake cmake patchelf qtcreator libfuse-dev libcairo2-dev
   

   Pull the source code

   git clone --recursive https://github.com/AppImage/AppImageKit
   git clone --recursive https://github.com/probonopd/linuxdeployqt …

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6. Rarely used git commands

   How to export all repository files to a directory?

   git --work-tree=${OUTPUT_DIRECTORY} --git-dir=${REPOSITORY_DIRECTORY}/.git checkout -f
   

   How to export all repository files to an archive?

   git archive --prefix="${result_directory}/" -o ${result_archive}.tar.gz HEAD
   

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7. How to forward GPU and sound to the host?

   Further in the article we will use demo as the user in the host and ubuntu in the container.

   Video

   Add the below lines to the LXD container config to allow the container's X11 to connect to the host:

   devices:
     Xauthority:
       path: /home/ubuntu/.Xauthority
       source: /home/demo/.Xauthority
       type …

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8. How to resolve apparmor or namespace permission issues?

   Some applications cannot work in containers because of apparmor permissions, namespaces or functionality unsupported by the kernel on the host system. Below is an example of a mariadb service error:

   mariadb.service: Failed to set up mount namespacing: Permission denied
   

   This error occurred when running the container in privileged mode …

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