Under the Ubuntu Software tab, make sure you have checked all of the Main, Universe, Restricted and Multiverse repository checked.

Tip: If the software updater returns an error, you should use the command “sudo apt update” in the terminal. The last few lines of the output will contain the actual error message. You can then search on the internet for that error and fix the problem.

By default, not all the available repositories are enabled on Ubuntu. Some of them contain closed-source applications and other copyrighted programs. Which is why they are not enabled by default.

However, if you want those programs (like Flash, codecs or Skype..). You can enable them. Simply open Synaptic, head to Settings —> Repositories. Make sure you have them activated like this:

Also make sure you enable this repository:

After you reload the package information (via Synaptic or sudo apt update command). You can now browse those repositories from Synaptic to see what software you may need:

Install Needed Drivers

Although I don’t personally like the closed-source hardware drivers, I have to admit that they – sometimes – give better performance. If you want this extra performance (especially if you are a gamer). You can install them from the drivers tab in Software Sources:

Some free drivers may be there as well.

Starting from Ubuntu 17.10, the system comes with GNOME desktop as default. If you would like to configure the interface’s options, you can install GNOME Tweak Tool:

sudo apt install gnome-tweak-tool

Since Ubuntu 17.10, Unity was dropped as a default desktop. However, if you are a fan of Unity, you can get it back via the following command:

sudo apt install unity unity-session

Install Unity Tweak Tool (If you use Unity)

Unity doesn’t come with a ready tool out-of-the-box to change the preferences of the desktop interface. This is where Unity Tweak Tool comes. It’s a very nice program to configure your desktop environment. Also available from the official repositories:

sudo apt install unity-tweak-tool

gdebi is a simple tool to install deb files. It lets you install local deb packages resolving and installing its dependencies.

sudo apt-get install gdebi

Since Ubuntu 18.10, the distribution comes with “Yaru” theme, which is really nice by default.

But if you don’t like it, there are hundreds of nice themes available on gnome-look.org. You can choose any one you like and download it.

If you are downloading a GTK+ theme, make sure to extract it to /home/yourusrename/.themes folder. Or if you are downloading an icon/mouse cursor theme, extract it to /home/yourusername/.icons. Those two folders (.themes and .icons) are hidden in your home folder. You need to open your home folder and hit Ctrl + H to show them. If they don’t exist, simply create them.

Some users – on some specific hardware – my notice a higher battery consumption rate on Linux than on Windows. The main and easiest thing you can do to solve this problem on Ubuntu, is simply installing TLP. Which is a nice power management system working in the background to save battery power when possible:

sudo apt-get install tlp tlp-rdw

sudo systemctl enable tlp

Then reboot your system.

Don’t like the default interface for Ubuntu? You can simply change it. You have many different possibilities: MATE, GNOME, KDE, XFCE, LXDE, LXQt, Budgie, Cinnamon.

Each interface has its own pros and cons. Just like tastes, everybody likes something different. You can check the look of each one of them to see which one is best for you.

Warning: Don’t install them all! Installing desktop environments like KDE and GNOME together is probably not a good idea on Ubuntu. Just install the one you would use on daily basis.

To install Cinnamon:

sudo apt install cinnamon-desktop-environment

To install KDE(with Kubuntu branding):

sudo apt kubuntu-desktop

To install Xfce:

sudo apt install xfce4

To install LXDE:

sudo apt install lxde

To install LXQt:

sudo apt install lxqt

To install Budgie:

sudo apt install budgie-desktop

Sometimes we may have different proprietary multimedia files and we would like to play them. Unfortunately, you will need to download another set of packages into your system. This is done via:

sudo apt install ubuntu-restricted-addons

If you like, you can install VLC which will ease your life a lot in playing multimedia files and URLs and doesn’t require the previous proprietary set of addons:

sudo apt install vlc

sudo apt install youtube-dl

Download a youtube video to mp3 format

$ youtube-dl --extract-audio --audio-format mp3 <video URL>

List all downloads available from a youtube video

$ youtube-dl -F <video URL>

Ocenaudio is free audio editor for Windows, Mac OS X and Linux.It is also based on Qt framework. Using ocenaudio you can edit and analyze audio files.It has a real time preview feature of your audio files. using this feature, you can hear the processed signal while adjusting the controls.

It supports multi-selection feature. With this amazing tool, you can simultaneously select different portions of an audio file and edit, listen or apply an effect.With this tool you can edit very large audio files. It also supports spectrogram view.

Go to the ocenaudio website and download the the latest version of ocenaudio in .deb file. After just double-click on'it.

Gamer? You should definitely try the available Linux games on Steam. Which are around 25% of the total games in the whole store. To install Steam on Ubuntu, download the .deb package from this link. Double click it and hit install.

To install the "old" Midnight Commander:

sudo apt install mc

To use in root mode : $ sudo mc

GNU Midnight Commander is a free cross-platform orthodox file manager. It was started by Miguel de Icaza in 1994 as a clone of the then-popular Norton Commander. GNU Midnight Commander is part of the GNU project and is licensed under the terms of the GNU.

GMAT is a software system for trajectory optimization, mission analysis, trajectory estimation, and prediction. Analysts use GMAT to design spacecraft trajectories, optimize maneuvers, perform orbit determination, visualize and communicate mission parameters, and understand a mission's trade space. GMAT contains models of real-world objects such as spacecraft and thrusters, as well as analysis "objects" such as plots and reports. These objects are used in the mission sequence wherein the user employs commands supported by the system to model missions and perform estimation.

In order to a stable and dynamic install of this program i advise run from /opt

1. First, boot into a new kernel.

2. List all other older kernel using the dpkg command.

3. Note down system disk space usage by running the df -H command.

4. Delete all unused old kernels, run: sudo apt --purge autoremove.

5. Verify it.

List all installed Linux kernel

Simply type the following dpkg command along with egrp command:

sudo dpkg --list | egrep -i --color 'linux-image|linux-headers'

Remove old kernel versions on Ubuntu 18.04 or above

Type the following apt command or apt-get command:

sudo apt --purge autoremove

OR

sudo apt-get --purge autoremove

The above commands only work on newer systems as all old Linux kernels and headers automatically flagged as no more needed, and thus can be purged.