Install VirtualBox under Ubuntu 19.10

You may have noticed that VirtualBox is having problems to install via the usual apt install method on Ubuntu 19.10. The reason is that it relies on old libraries from Ubuntu 19.04 which conflict with the current ones. When having such problems with compatibility there is also interesting solutions.
Reference: Practical Ubuntu Linux Server for beginners
You can watch the video for more details:

First, uninstall any previous VirtualBox leftovers that you might have with sudo apt remove virtualbox
Just go to https://www.virtualbox.org/wiki/Testbuilds and download the test build for Linux64-bit
then do: chmod +x file.run (where the file is the downloaded file)
and just run: sudo ./file.run

And that's it, the installer will run and you'll have the newest version of VirtualBox under Ubuntu 19.10 running.

Notes:
- Please also check the version of your kernel (uname -r), for now, Virtualbox supports kernel 5.3, so playing on anything above this version will also not allow Virtualbox modules to be compiled into the kernel and run.
- Your further virtual machines will reside inside the /root/ directory
- In order to remove the VirtualBox, you can run ./file.run uninstall

Congratulations!

Optimize Ubuntu for speed and performance

Here are some ways to optimize your Ubuntu system to take fewer resources and to be more performant. If you are interested there is a complete course on ubuntu administration.

You can take a look at the video:

I advise you at first to take a look at Conky as a hardware monitoring application
sudo apt install conky-all
and then run conky
From there just monitor which resources are fully utilized such as Disks, CPU, and Memory. This way you can really understand if you need to buy new hardware.

2. Use Lubuntu
sudo apt install lubuntu-desktop
you will be amazed by the performance gains.

3. Clean up your system using bleachbit
https://www.bleachbit.org/download

4. Tab wrangler - this addon to Firefox or Chrome will stop any inactive tabs, thus freeing up precious memory

5. Services:
systemd-analyze blame - will output all the services loading at bootup and which are taking most of the time. Feel free to disable with systemctl disable service_name those that you don't want.
You can inspect why certain service takes too long by typing:
systemctl status udisks2
and then
systemd-analyze critical-chain udisks2.service
(here we are inspecting the udisks2.service)
journalctl -b | grep udisks2
will show you even more detailed information about a particular service
Additional:
- You can also disable package indexing with sudo apt-get purge apt-xapian-index
- If you are not using thin clients, or have servers that need internet access for boot/configuration  you can also do:
sudo systemctl disable NetworkManager-wait-online.service
- Do check if UUID's listed in blkid and /etc/fstab match up and edit /etc/fstab to match accordingly.

Extra note: Install kernel modification such as Xanmod, which optimizes the performance to be suited for Desktop users:
echo 'deb http://deb.xanmod.org releases main' | sudo tee /etc/apt/sources.list.d/xanmod-kernel.list && wget -qO - https://dl.xanmod.org/gpg.key | sudo apt-key add - 
sudo apt update && sudo apt install linux-xanmod
I am really impressed by the performance of this kernel mod.

Congratulations and enjoy the course.