In most cases, the default installation of Red Hat Enterprise Linux configures a machine to boot into a graphical login environment, known as runlevel 5. It is possible, however, to boot into the text-only multi-user mode called runlevel 3 and begin an X session from there.

For more information about runlevels, refer to Section 1.4, “SysV Init Runlevels”.

The following subsections review how X starts up in both runlevel 3 and runlevel 5.