In Linux a lot of things can be done in the Terminal, but most people seem more comfortable in using a Graphical User Interface (GUI). In this article we will cover the steps to add the MATE GUI to a CentOS 7 and Ubuntu 14.04 system for the LFCS certification. CentOS 7 GUI Installation For CentOS you need to log in to your system using the username and password you created during the Operating System (OS) install. Once you are at a terminal command prompt, enter the following commands: 1. sudo yum install epel-release NOTE: At the time this article was written 'epel-release' was not available for CentOS 7 32-bit. Since the add-on is not available, then MATE cannot be added to CentOS 7 32-bit. 2. sudo yum groupinstall “X Window System” 3. sudo yum groupinstall “MATE Desktop” NOTE: The commands are case-sensitive. If any prompts are shown for downloading the files press 'y' to accept the download. The commands will install the X Windows System and then the MATE Desktop. To run the desktop GUI you need to type in the following command: systemctl isolate graphical.target At this point MATE should start, similar to Figure 1, and you are prompted to log into the GUI system. When CentOS is started you will return to a command prompt and have to start the GUI each time the system is restarted. To fix the issue, open a terminal and type the command: systemctl set-default graphical.target FIGURE 1 NOTE: The execution of the command will require you to enter the ROOT password twice, - once for removing the current default and the second for making the new default to the MATE desktop. Now MATE is set as the default GUI to load at CentOS startup. Ubuntu 14.01 GUI Installation For Ubuntu you need to log in to your system using the username and password you created during the OS installation. Once you are at a terminal command prompt enter the following commands: 1. sudo apt-get install software-properties-common 2. sudo apt-add-repository ppa:ubuntu-mate-dev/ppa 3. sudo apt-add-repository ppa:ubuntu-mate-dev/trusty-mate 4. sudo apt-get update 5. sudo apt-get upgrade 6. sudo apt-get install mate-desktop-environment 7. sudo apt-get install mate-desktop-environment-extras 8. sudo apt-get install lightdm lightdm-gtk-greeter 9. sudo reboot The last command causes a reboot and when the system restarts you should be prompted for you password. Once logged in you should see the same desktop as shown in Figure 2 (some icons may vary depending on disk drives). FIGURE 2 Post Installation At this point you can install any other items you may need on the system, such as applications or utilities. You may want to leave the system as is and follow along through the articles. Make sure you practice the steps set out in the articles to make sure you are familiar and comfortable with them. It is imperative to know the steps so you can easily perform them on the exam if you plan to take it. It is a special note to know that you have access to the MAN (help) pages during the exam, but it is still good to know what you are doing. NOTE: If the network stops in VirtualBox and the virtual machine cannot access the Internet change Adapter 1 to NAT. Guest Additions for VirtualBox Once the GUI is in place you can add the Guest Additions. Once VirtualBox is loaded and your virtual machine is started, then select 'Devices' and at the bottom of the menu click on 'Insert Guest Additions CD Image…'. The image should be loaded as a CD in the OS and a screen similar to Figure 3 should appear. FIGURE 3 If you should have a problem seeing the menu to select 'Devices' then try pressing the Right CTRL and either 'F' or 'C' to change the View Mode. Once the menu to show the Guest Additions have been added, click on 'OK' to start the installation. You may need to enter your password multiple times to allow the installation to proceed. Once the installation is completed you can Unmount the CD and the Guest Additions are ready to be used. Install Guest Additions without GUI I may have mentioned a few times that the GUI is required to install the Guest Additions. True, it is easier to do the installation through the GUI, but they can be added through the command-line. I still suggest to do it through the GUI, but let's look at it from a CentOS 7 32-bit point of view since MATE cannot be installed on it. NOTE: Other desktop GUIs can be installed, but MATE is suggested for the exam. I do not suggest using the 32-bit version of CentOS 7 for learning to use for the LFCS certification. If you want to use CentOS 7 for the exam then you should use the 64-bit version (and for Ubuntu as well). Just to cover the installation through a command-line I will cover this on the 32-bit CentOS 7 VirtualBox install. Once CentOS is installed under VirtualBox start the virtual machine. Login with the credentials you created during the installation. If you do not see a menu, then hold down the Right CTRL button and press HOME. The menu should appear. Under 'Devices' select 'Insert Guest Additions CD Image…'. You need a directory for the mount point, so create a folder named 'cdrom' in the 'media' folder with the command: sudo mkdir /media/cdrom Next, you will mount the CD to the new folder with the command: sudo mount /dev/cdrom /media/cdrom When the CD is mounted you will need to change to the CDROM with the command: cd /media/cdrom NOTE: Without the GUI installed you may need to install 'bzip2' for the Guest Additions. To do this, use the command: sudo yum install bzip2. You will also need to run sudo yum install gcc*. All the dependencies should be installed as mentioned in the previous article. Whether you are running Ubuntu or CentOS the command to start the Guest Additions, installation is: sudo ./VboxLinuxAdditions.run You should get a message about no X.Org or XFree86 Window System found, but Guest Additions are still installed. To check on the version of the Guest Additions installed on your system open a terminal and type the command 'ls /opt'. One of the output folders listed should be similar to 'VboxGuestAdditions-5.1.10'. The version of the Guest Additions in this example is 5.1.10.