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System must be configured properly, as described in Chapter 35, The X Window System
(page 509), before the runlevel can be switched to 5. If this is done, check whether the
system works in the desired way by entering init 5. If everything turns out as expected, you can use YaST to set the default runlevel to 5.
WARNING: Errors in /etc/inittab May Result in a Faulty System Boot
If /etc/inittab is damaged, the system might not boot properly. Therefore,
be extremely careful while editing /etc/inittab and always keep a backup
of an intact version. To repair damage, try entering init=/bin/sh after the
kernel name at the boot prompt to boot directly into a shell. After that, make
your root file system writable with the command mount -o remount,rw
/ and replace /etc/inittab with your backup version using cp. To prevent
file system errors, change your root file system to read-only before you reboot
with mount -o remount,ro /.
Generally, two things happen when you change runlevels. First, stop scripts of the
current runlevel are launched, closing down some programs essential for the current
runlevel. Then start scripts of the new runlevel are started. Here, in most cases, a number
of programs are started. For example, the following occurs when changing from runlevel
3 to 5:
1.
The administrator (root) requests init to change to a different runlevel by entering init 5.
2.
init consults its configuration file (/etc/inittab) and determines it should
start /etc/init.d/rc with the new runlevel as a parameter.
3.
Now rc calls all the stop scripts of the current runlevel, but only those for which
there is no start script in the new runlevel. In this example, these are all the scripts
that reside in /etc/init.d/rc3.d (old runlevel was 3) and start with a K.
The number following K specifies the order to start, because there are some dependencies to consider.
4.
The last things to start are the start scripts of the new runlevel. These are, in this
example, in /etc/init.d/rc5.d and begin with an S. The same procedure
regarding the order in which they are started is applied here.
Booting and Configuring a Linux System
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