After booting, you will be prompted to complete the configuration of your basic system, and then to select what additional packages you wish to install. The application which guides you through this process is called base-config. Its concept is very similar to the debian-installer from the first stage. Indeed, base-config consists of a number of specialized components, where each component handles one configuration task, contains “hidden menu in the background” and also uses the same navigation system.
If you wish to re-run the base-config at any point after installation is complete, as root run base-config.
After a welcome screen, you will be prompted to configure your time zone. First select whether the hardware clock of your system is set to local time or Greenwich Mean Time (GMT or UTC). The time displayed in the dialog may help you decide on the correct option. Macintosh hardware clocks are normally set to local time. If you want to dual-boot, select local time instead of GMT. This question will not be asked if Ubuntu is the only operating system installed on your computer; base-config will then simply default to UTC.
Depending on the location selected at the beginning of the installation process, you will next be shown either a single timezone or a list of timezones relevant for that location. If a single timezone is shown, chooseto confirm or choose to select from the full list of timezones. If a list is shown, select your timezone from the list, or select Other for the full list.
The system will ask you whether you wish to create an ordinary user account at this point. This account should be your main personal log-in.
The account you create at this point will be given root privileges by means of the sudo command, and the root account itself will have login disabled. If you wish, you can enable the root account later by setting a password for it with the command sudo passwd root.
You should not use the root account for daily use or as your personal login, nor should you use sudo except when root privileges are really required.
Why not? Well, one reason to avoid using root's privileges is that it is very easy to do irreparable damage as root. Another reason is that you might be tricked into running a Trojan-horse program — that is a program that takes advantage of your super-user powers to compromise the security of your system behind your back. Any good book on Unix system administration will cover this topic in more detail — consider reading one if it is new to you.
You will first be prompted for the user's full name. Then you'll be asked for a name for the user account; generally your first name or something similar will suffice and indeed will be the default. Finally, you will be prompted for a password for this account.
If at any point after installation you would like to create another account, use the adduser command.
The main means that people use to install packages on their system is via a program called apt-get, from the apt package. APT must be configured, however, so that it knows where to retrieve packages from. The helper application which assists in this task is called apt-setup.
The next step in your configuration process is to tell APT where other Ubuntu packages can be found. Note that you can re-run this tool at any point after installation by running apt-setup, or by manually editing /etc/apt/sources.list.
If an official CD-ROM is in the drive at this point, then that CD-ROM should automatically be configured as an apt source without prompting. You will notice this because you will see the CD-ROM being scanned.
For users without an official CD-ROM, you will be offered an array of choices for how Ubuntu packages are accessed: FTP, HTTP, CD-ROM, or a local file system.
You should know that it's perfectly acceptable to have a number of different APT sources, even for the same Ubuntu archive. apt-get will automatically pick the package with the highest version number given all the available versions. Or, for instance, if you have both an HTTP and a CD-ROM APT source, apt-get should automatically use the local CD-ROM when possible, and only resort to HTTP if a newer version is available there. However, it is not a good idea to add unnecessary APT sources, since this will tend to slow down the process of checking the network archives for new versions.
If you plan on installing the rest of your system via the network, the most common option is to select the http source. The ftp source is also acceptable, but tends to be a little slower making connections.
The next step during the configuration of network packages sources is to tell apt-setup which country you live in. This configures which of the official Ubuntu Internet mirror network you connect to. Depending on which country you select, you will be given a list of possible machines. It's generally fine to pick the one on the top of the list, but any of them should work.
If you are installing via HTTP, you will be asked to configure your proxy server. This is sometimes required by people behind firewalls, on corporate networks, etc.
Finally, your new network package source will be tested. If all goes well, you will be prompted whether you want to do it all over again with another network source.
Unless you booted the installer using the custom option, base-config will now automatically install the set of packages that make up the Ubuntu desktop. A few questions may be asked during this process in case the X Window System configuration tools are unable to automatically detect your keyboard layout, graphics card, or optimum screen resolution.
Aptitude is a modern program for managing packages. aptitude allows you to select individual packages, set of packages matching given criteria (for advanced users), or whole tasks.
The most basic keybindings are:
|Up, Down||Move selection up or down.|
|+||Mark package for installation.|
|-||Mark package for removal.|
|d||Show package dependencies.|
|g||Actually download/install/remove packages.|
|q||Quit current view.|
For more commands see the online help under the ? key.
Each package you selected with tasksel or aptitude is downloaded, unpacked and then installed in turn by the apt-get and dpkg programs. If a particular program needs more information from the user, it will prompt you during this process. You might also want to keep an eye on the output during the process, to watch for any installation errors (although you will be asked to acknowledge errors which prevented a package's installation).
On iMacs, and some older Macintoshes as well, the X Server software doesn't calculate appropriate video settings. You will need to choose the 'Advanced' option during configuration of the video settings. For the monitor's horizontal sync range, enter 59-63. You can leave the default for vertical refresh range.
The mouse device should be set to /dev/input/mice.
 Note that the actual program that installs packages is called dpkg. However, this package is more of a low-level tool. apt-get will invoke dpkg as appropriate; it is a higher-level too, however, because it knows to install other packages which are required for the package you're trying to install, as well as how to retrieve the package from your CD, the network, or wherever.