You can also start X sessions from the command line. The following sections
describe these two methods.
NOTE
If you have used the Server install, your system boots to a text login. See
Chapter 10, “Command-Line Beginner’s Class,” for more information
about what to do here.Using a Display Manager
An X display manager presents a graphical login that requires a username and
password to be entered before access is granted to the X desktop. It also
enables you to choose a different desktop for your X session. Whether an X
display manager is presented after you boot Linux is controlled by a runlevel
—a system state entry in /etc/event.d/. The following runlevels are
handled by Ubuntu:
0—Halt (Do not set initdefault to this.)
1—Multiuser text mode
2—X graphical multiuser mode
6—Reboot (Do not set initdefault to this.)You may see mention of runlevels 3 through 5; you can ignore these because
they are treated the same as runlevel 2 in Ubuntu. Historically, Ubuntu used
the /etc/inittab file to handle runlevels, but this file no longer exists.
(See Chapter 15, “The Boot Process,” for information about runlevels.)
Instead, there are several files under the /etc/events.d/ directory,
including an individual file for each of the virtual consoles (accessible by
pressing Ctrl+Alt+F1 to F7). However, you can still create an inittab file
if you want to override any defaults held by Ubuntu. Make sure you create the
inittab file as root and include at least one line similar to the following:
id:1:initdefault:This forces your system to start up in text mode.
Changing Window Managers
Ubuntu makes it fairly painless to switch to another window manager or
desktop environment. Desktop environment refers to not only the window
manager but also the suite of related applications, such as productivity or