Installing Packages/Applications/Software

The yum (apt-get or apt in Ubuntu) command is used to install new packages and to update/upgrade the operating system, it requires administrative access, so it must be used with sudo.


The operating system must be updated on a regular basis, this way you will keep your data and integrity of the system safe. In order to update your system, run one of the following commands:

yum update
apt-get update 

yum upgrade (updates the obsolete packages too)
apt-get upgrade (Ubuntu)

After the system is updated you can run yum clean, to erase the files that were left after the packages installed.
apt-get autoremove (Ubuntu)
apt-get autoclean (Ubuntu)
apt-get clean (Ubuntu)

To search for a specific package/application/software in the repository (we will search for inkscape – a graphic software) use: yum search inkscape (apt-get search inkscape in Ubuntu) and to install it run: yum install inkscape (apt-get install inkscape in Ubuntu). And if you no longer need it: yum erase inkscape (apt-get remove inkscape in Ubuntu). (use: yum reinstall inkscape in case you deleted it by mistake)

By default the Linux repository contains only packages that are considered stable, but we will see later in this tutorial, how to modify the repository and add more packages.

Shutdown command

The shutdown command is used to prepare the system to turn off in a safe way, all logged in users will be anounced that the system will be turned off and in the last 5 minutes new logins are blocked.


Please note that the shutdown command requires administrative access, so you must login with the root user: su root

The argument [TIME] can accept the following options: now, hh:mm, +minutes

To see the current date/time and date/time format of your system run this command in the console: date

Do a few exercises:

shudown 08:32

shutdown +3 “Bye Bye!”

To stop a shutdown command you must use: shutdown -c

Su users can also use this command in order to issue a restart:


shutdown -r now 


Make sure you save your work before you run commands like restart or shutdown.

Useful links:

Most used Linux commands

Linux Directory Map / Structure

Introduction to Linux

Using Help in Linux

Download and install Oracle VirtualBox

How to install CentOS on Oracle VirtualBox