Translations by Marcin Pianka

\marginnote{Note that loading images may provide a way for the sender to track your receipt of the message. We do not recommend loading images in messages that you suspect are Junk.}

To manually configure a wired connection, right-click on the NetworkManager icon and select \menu{Edit Connections}. Make sure you are looking at the \button{Wired} tab inside the \window{Network Connections} window that is displayed.

\marginnote{Are you already online? If the NetworkManager icon in the top panel shows a connection, then you may have successfully connected during the installation process. If so, you do not need to follow the rest of this section.}

You can also right-click on the NetworkManager icon. This will open a menu allowing you to enable or disable networking, view technical details about your current connection, or edit all connection settings. In the image above, the check box next to ``Enable Networking'' is currently selected; you can deselect it to disable all network connections. This may be useful if you need to shut off all wireless communication, such as when in an airplane.

\marginnote{Check out the \emph{Featured Applications} department to see a list of highly recommended applications.}

The \application{Software Center} can be used to install most applications that are available in the official Ubuntu repositories.

\marginnote{Some software packages have more advanced purposes, such as programming or running a \gls{server}, and cannot be installed using the \application{Software Center}. You will need to use the \application{Synaptic Package Manager} (discussed towards the end of this chapter) to install these packages.}

Although the \application{Software Center} provides a large library of applications to choose from, initially only those packages available within the official Ubuntu repositories are listed. At times, a particular application you are after may not be available in these repositories. If this happens, it is important to understand some alternative methods for accessing and installing software in Ubuntu, such as downloading an installation file manually from the internet, or adding extra repositories. First, we will look at how to manage your repositories through \application{Software Sources}.

\emph{Type your password into the authentication window that appears.} Removing software also requires that you enter your password to help protect your computer against unauthorized changes. The package will then be queued for removal, and will appear under the \tab{In Progress} section in the sidebar.

Removing applications is very similar to installing them. First, click on the \button{Installed Software} button in the \application{Software Center's} sidebar. Scroll down to the application you wish to remove (or use the search field to quickly find it), and then:

\emph{Click the \button{Remove} button} to the right of the selected application. \notecallout{To completely remove a package and all its configuration, you will need to \emph{purge} it. You can do this with the more advanced \application{Synaptic Package Manager}, which is discussed further in the \seclink{sec:synaptic} section below.}

\marginnote{Note that you will need to be connected to the Internet for the Software Center to work. To learn how to set up your connection, see \chaplink{ch:default-applications}.}

\emph{Wait until the package is finished installing}. During the installation (or removal) of software packages, you will see an animated icon of rotating arrows to the left of the \tab{In Progress} button in the sidebar. If you like, you can now go back to the main browsing window and queue additional software packages to be installed by following the steps above. At any time, clicking the \button{In Progress} button on the left will take you to a summary of all operations that are currently processing. Here you can also click the \textsf{X} icon to cancel any operation.

Once the \application{Software Center} has finished installing an application, it is now ready to be used. Ubuntu will place a launcher in your \menu{Applications} menu under the relevant sub-menu\dash its exact location will depend on the purpose of the application. If you cannot find it, in some cases an application will appear in one of the \menu{System\then Preferences} or \menu{System\then Administration} menus instead.

\emph{Type your password into the authentication window that appears.} This is the same password you use to log in to your account. You are required to enter it whenever installing new software, in order to prevent someone without administrator access from making unauthorized changes to your computer. \notecallout{If you receive an ``Authentication Failure'' message after typing in your password, check that you typed it correctly by trying again. If the error continues, this may mean that your account is not authorized to install software on the computer.}

\emph{Click the \button{Install} button to the right of the selected package.} If you would like to read more about the software package before installing it, first click on \button{More Info}. This will take you to a short description of the application, as well as a screenshot and a web link when available. If you wish to proceed, you can also click \button{Install} from this page.

When you are ready marking actions, click the \button{Apply} button and wait until the changes are made. Afterwards, you can close the application or mark more changes.

To open the \application{Synaptic Package Manager}, navigate to \menu{System \then Administration \then Synaptic Package Manager}. As explained above, \application{Synaptic} is a more complex tool than the \application{Software Center}, and generally not essential for a new user just getting started with Ubuntu. If you want to read more information on how to use this program, or require more support managing the software on your system, head to \url{https://help.ubuntu.com/community/SynapticHowto}.

\notecallout{The If you are not very familiar with advanced computing in Ubuntu you may wish to stick with the \application{Software Center}.}

\textbf{Purge}. This is when you wish to completely remove a package, including any stored preferences or configuration files (which are often left behind when a package is removed).

Most operating systems, including Ubuntu, have two types of user interfaces. The first is a graphical user interface (\acronym{GUI}). This is the desktop, windows, menus, and toolbars that you click to get things done. The second, and much older, type of interface is the command-line interface (\acronym{CLI}).

\notecallout{Every 6 months, Ubuntu releases a new version of the operating system. These are called \textit{normal releases}. Every four normal releases\dash or 24 months\dash Ubuntu releases a \textit{Long Term Support (LTS)} release. Long Term Support releases are intended to be the most stable releases available, and are supported for longer.}

The rest of this chapter covers some very common uses of the terminal, however, there are almost infinite possibilities available to you when using the command-line interface in Ubuntu. Throughout the second part of this manual we will continue to refer to the command line, particularly when discussing steps involved in troubleshooting and the more advanced management of your computer.

You can open the terminal by clicking \menu{Applications \then Accessories \then Terminal}.

Getting started with the command line

\application{Nautilus File Manager} will automatically add a shortcut to the mounted device in the side bar so it's easy for you to get to. You shouldn't have to physically navigate to the \emph{media} directory in Ubuntu.

The \commandlineapp{pwd} command is short for \emph{print working directory}. It can be used to display the directory you are currently in. Note that the prompt (the text just before the blinking cursor) also displays your current directory, so this command is not usually necessary.

When a device such as a \acronym{USB} flash drive or a media player is mounted in Ubuntu, a folder is created for it under \emph{media} and you are given the appropriate permissions to be able to read and write to the device.

Navigating directories

Mounting and unmounting removable devices.

Ubuntu uses the Linux file system structure based on a series of folders in the root directory. Each of these folders contain important system files that cannot be modified unless you are running as the root user or use \emph{sudo}. This is for both security and safety reasons so that viruses cannot access the core system files, and users cannot damage anything.

\prompt \userinput{rm /tmp/example/deleteme.txt}

To delete a file located in another directory (\ie, not inside your current working directory), you would need to include the \emph{path} to the file. In other words, you are specifying the file's location. For example, to delete the file \texttt{deleteme.txt} located in the \texttt{/tmp/example} directory, use the following command:

The \commandlineapp{rmdir} command is similar to the \commandlineapp{rm} command, except it is used to delete folders. For example, this command would delete the directory called \texttt{newdirectory} that we created earlier.

Introducing sudo

\commandlineapp{Apt-get} is used for installing and removing packages from your system. It can also be used to refresh the list of packages available in the repositories, as well as download and install any new updates for your software.

Using apt-get

In Ubuntu there are a number of ways to manage your software. \acronym{GUI} tools such as the \application{Ubuntu Software Center} and \application{Synaptic Package Manager} were discussed in \chaplink{ch:software-management}, however, many people prefer to use the \commandlineapp{apt} command (Advanced Packaging Tool) to manage their software from within the terminal. \commandlineapp{Apt} is extremely versatile and encompasses several tools, however, the most commonly used \commandlineapp{apt} tool is \commandlineapp{apt-get}.

\prompt \userinput{sudo gedit} [sudo] password for \emph{username}: Opening gedit\ldots

\warning{The {\ttfamily sudo} command gives you virtually unlimited access to important system files and settings. It is important you only use {\ttfamily sudo} if you understand what you are doing. You can find out more about using {\ttfamily sudo} in \chaplink{ch:security}.}

Managing software through the terminal

\marginnote{When using \commandlineapp{sudo} in the terminal, you will be prompted to enter your password. You will not see any dots, stars, or other characters appearing in the terminal as you type your password, however, don't be put off\dash this is an extra security feature to help protect you from any prying eyes.}

For example, the following command would open Ubuntu's default text editor \application{gedit} with root privileges. You will then be able to edit important system files that would otherwise be protected. The password you use with \commandlineapp{sudo} is the same password that you use to log in to your primary account, and is set up during the Ubuntu installation process.

When Ubuntu is first installed two accounts are created: your primary user account, and a ``root'' account that operates behind the scenes. This root account has the necessary privileges required for modifying system files and settings, whereas your primary user account does not. Rather than logging out of your primary user account and then logging back in as root, you can use the \commandlineapp{sudo} command to borrow root account privileges for performing administrative tasks such as installing or removing software, creating or removing new users, and modifying system files.

Often software in Ubuntu depends on other packages being installed on your system in order to run correctly. If you attempt to install a new package and these \emph{dependencies} are not already installed, Ubuntu will automatically download and install them for you at the same time (provided the correct packages can be found in your repositories). When you remove a package in Ubuntu, however, any dependencies that were installed alongside the original package are not also automatically removed. These packages sit in your system and can build up over time, taking up disk space. A simple way to clean up your system is to use the \commandlineapp{apt-get} \code{autoremove} command. This will select and remove any packages that were automatically installed but no longer required.

Select a user from the list and click \button{Delete}. Ubuntu will deactivate the user's account, though it will not remove the user's home folder.

To add a group, click \button{Add}. In the dialog that appears, enter the group name and select the names of users you'd like to add to the group.

To adjust the user and group settings click the keys icon next the phrase ``Click to make changes.'' You will need to input your password in order to make changes to user and group settings.

Click the \button{Add} button which appears underneath a list of the current user accounts that have already been created. Type in the new username and select relevant options then click \button{OK}. A new dialog box will appear asking you to enter a password for the user you have just created. Fill out the fields, then click \button{OK} to proceed. Privileges you grant to the new user can be altered in \window{Users Settings}.

Like most operating systems, Ubuntu allows you to create users accounts for multiple people, each with some access to your computer. Ubuntu also supports user groups, which allow you to administer permissions for multiple users at the same time.