Guest Linux OS

The follwoing are the instructions to create a Linux computer that students can log into as a "Guest", where the home directory is just mounted to a RAM disk. This way as each new student logs in, the "Guest" account is completly fresh and has no saved data. But the students still have access to all the locally loaded programs.

Install base OS

• NOTE: Ensure the hard drive is the SMALLEST size of all the machines you will clone. You can not clone a larger drive onto a smaller one. You can clone a smaller one onto a larger one though.
• for this installation I am using Debian 13, Trixie
  • downlaod the latest ISO and burn it to a USB
  • go through the standard install
    • host is: "cs"
    • ensure you pick "gnome" desktop and "ssh server" would also be helpful
  • for the user create:
    • login: guest
  • remember that the "guest" user by default does not have "sudo" privileges and that is what we what, DO NOT give guest "sudo" access

Change Power Settings

• login as "root"
• run this command:

systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target

Cleanup Boot Screen

• login as "root"
• to remove as much "linux text" startup screen:
  • in "/etc/default/grub" file change:

  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash loglevel=3"
  GRUB_TIMEOUT=0
  GRUB_TIMEOUT_STYLE=hidden
  GRUB_RECORDFAIL_TIMEOUT=0

• then to make the change permanent:

update-grub

Mount /home/guest to RAM

• to make the "guest" user home directory in RAM we will use "tmpfs"
  • login as "root"
  • in /etc/fstab, add the following to the end:

  tmpfs  /home/guest  tmpfs  defaults,size=1G,mode=0700,uid=guest,gid=guest  0  0

  • Since the RAM disk is wiped every reboot, the guest user won't have a .bashrc or desktop folders. You can use systemd-tmpfiles to automatically copy default files from /etc/skel every time the machine boots.
    • nano /etc/tmpfiles.d/guest-home.conf

    C  /home/guest  -  -  -  -  /etc/skel
    Z  /home/guest  -  guest  guest  -  -

  • Clear out any existing physical files in the guest home to avoid conflicts:

    rm -rf /home/guest/*

  • Mount the new RAM disk:

    systemctl daemon-reload
    mount /home/guest

  • Now, every time you reboot, any files the "guest" user creates will vanish, and a fresh set of default files from /etc/skel will be waiting for them.

Load APT Software

• login as "root"
• load the following software:
  • python "python-is-python3 python3-pip black"
  • java "default-jdk"
  • C & C++ "build-essential gdb cpplint"
  • GBDK "libgc1c mgba-qt"

  apt install git curl neovim python-is-python3 python3-pip black default-jdk build-essential gdb cpplint arduino freecad gimp mgba-qt -y

Load VS Code

• login as "root"
• goto VS Code downloads webpage and get the AMD64 deb version:
• get it from: https://packages.microsoft.com/repos/vscode/pool/main/c/code/
• this version "code_1.108.0-1767881962_amd64.deb" is a good pinned version, it allows AI to be turned off but does not have the "popup" on 1st start

  wget https://packages.microsoft.com/repos/vscode/pool/main/c/code/code_1.108.0-1767881962_amd64.deb
  apt install ./code_1.108.0-1767881962_amd64.deb

Load CS50 Library

• login as "root"
• Download the latest release from https://github.com/cs50/libcs50/releases
• Extract libcs50-.: tar -xvzf ./v...

  mkdir /tmp/cs50
  cd /tmp/cs50
  wget https://github.com/cs50/libcs50/archive/refs/tags/v11.0.3.tar.gz
  tar -xvzf ./v11.0.3.tar.gz
  cd libcs50-11.0.3
  make install
  cd /tmp

Load GBDK Library

• login as "root"
• Download the latest release from https://github.com/gbdk-2020/gbdk-2020/releases

  mkdir /tmp/gbdk
  cd /tmp/gbdk
  wget https://github.com/gbdk-2020/gbdk-2020/releases/download/4.5.0/gbdk-linux64.tar.gz
  tar -zxf gbdk-linux64.tar.gz --directory /usr/bin/
  cd /tmp
  sh -c "echo 'export PATH=\$PATH:/usr/bin/gbdk/bin' >> /etc/skel/.bashrc"

Install MicroBlocks

• login as "root":
• run this:

wget https://microblocks.fun/downloads/latest/packages/ublocks-amd64.deb
apt install ./ublocks-amd64.deb -y

• follow these instructions: https://microblocks.fun/get-started:

usermod -a -G dialout guest
usermod -a -G tty guest

FireFox Fix

• create file:

  nano /usr/lib/firefox-esr/distribution/policies.json

• add in:

  {
    "policies": {
      "OverrideFirstRunPage": "",
      "OverridePostUpdatePage": "",
      "DontCheckDefaultBrowser": true,
      "DisableTelemetry": true,
      "NoDefaultBookmarks": true
    }
  }

• edit file:

  nano /etc/firefox-esr/firefox-esr.js

• add in:

  // startup tabs
  pref("browser.startup.homepage", "http://172.22.52.50|https://gmail.com");

Change Guest's Dot Files

• login as "root"
• goto "/etc/skel":

  mkdir -p /etc/skel/.config/Code/User/
  nano /etc/skel/.config/Code/User/settings.json

  -> Paste your JSON settings into this file -> then to "rehydrate the home directory":

  rm -rf /home/guest/*

Load VS Code Extensions

• see instructions on other page

Remove Gnome Tour

• login as "root"
• unistall the "tour" app

apt remove gnome-tour -y

Set Guest to Dark Mode

• login as "root"
• run:

  mkdir -p /etc/dconf/db/local.d/
  nano /etc/dconf/db/local.d/01-dark-mode

• add in:

  [org/gnome/desktop/interface]
  color-scheme='prefer-dark'
  gtk-theme='Adwaita-dark'

Set Gnome Toolbar

• login as "root"

• create file /etc/dconf/profile/user:

  user-db:user
  system-db:local

• create a file named /etc/dconf/db/local.d/00-favorite-apps:

  [org/gnome/shell]
  favorite-apps=['firefox-esr.desktop', 'org.gnome.Nautilus.desktop', 'code.desktop']

• update:

  dconf update

Set Git user Name and Email

• login as "root"
• run:

  git config --system user.name "Guest student"
  git config --system user.email "guest.student@stu.ocsb.ca"
  git config --global credential.helper 'cache --timeout=5400'

Now lock Debian APT from Updating!

• login as "root"

• run:

  systemctl disable --now apt-daily.timer apt-daily-upgrade.timer
  systemctl mask apt-daily.timer apt-daily-upgrade.timer

• edit this file: nano /etc/apt/preferences.d/99-lock-everything

Package: *
Pin: release *
Pin-Priority: -1