Initial Setup
https://wiki.switchroot.org/en/Linux/Ubuntu-Install-Guide
If you are using a Nintendo Switch on L4T Ubuntu 3.4.0 or newer, you already have the L4T Megascript. Search your applications list for the 
icon.
Option A (no terminal use needed, update to L4T 3.4.0+ for use on Nintendo Switch only - not applicable to other Tegra hardware):
1. If you're already using 5.0.0, go directly to step 2. However, if you're on an older version (3.3.0 or lower), open the "Software Updater" app and click "Install now" or run the following in terminal sudo apt update && sudo apt-get dist-upgrade, update hekate to 6.0.1 or newer, and reboot.
2. Dump joycon pairing info in hekate (if you haven't ever done so).
3. Boot your Switch and you will have the L4T Megascript in your applications list, which you can select to run the Megascript.
Option B (works for Nvidia Jetson users on 18.04+ and Fedora users - run the Megascript directly from the terminal just once and get an app icon for future launches):
Boot L4T on your device and open a terminal (Ctrl + Alt + T or open Terminal from the app list), then copy and paste the following command to automatically update dependencies and run the Megascript: (Hint: We've got a fully functional headless mode! If running over SSH with no display, remove "gui" - just bear in mind that you can't batch install programs in this interface.)
bash <( wget -O - https://raw.githubusercontent.com/cobalt2727/L4T-Megascript/master/core_refactor2.sh ) "gui"
Note: do not run this command with sudo - the script will prompt for admin access as needed.
An L4T Megascript application will be added to your system when you run the Megascript for the first time.
This can be found at /usr/share/applications/ if you want to remove our .desktop file later, for any reason.
You are running an old and unsupported version of L4T Ubuntu, and should definitely update for the best experience.
First fix your apt repos by running sudo sed -E -i 's/turul.canonical/ports.ubuntu/g' /etc/apt/sources.list
Then, follow the steps above, Option A
A few additional scripts are run on first use of the L4T-Megascript to ensure everything is in working order.
Currently the scripts include:
Workaround permissions issues due to options not supported in L4T Kernel
Install custom Tegra BSP Flatpak for GPU hardware acceleration (you can find the sources for that here).
BSP 32.3.1, 32.7.3, 35.1.0, 35.2.1, and 35.3.1 supported on T210, T186, T194, and T234. If you are a developer and the version of the BSP you need is not supported, follow the sources above to package your own alternative BSP or ask in our Discord server for help.
Snaps have no hardware acceleration and we don't recommend that you use Snaps at all
Installs SDL2.26.1 Debian binaries compiled on Ubuntu Bionic (http://deb.debian.org/debian/pool/main/libs/libsdl2/libsdl2_2.26.1+dfsg-1.dsc).
SRB2, SRB2Kart, SuperTux2, Celeste (Pico-8 Port), Flappy Bird, SM64 Port, RetroPie, Box64
And that's all! You're all set to install just about any other program included in the Megascript. Check the individual wiki pages to read more on a particular game or program.
If possible, you definitely want to hook up a USB keyboard and/or mouse to make setup easier...