After starting this YaST module, it displays an overview listing all the available services and the current status of each service — whether they are enabled or not. With the radio buttons, decide whether to use the module in ‘Simple Mode’ or in ‘Expert Mode’. The default ‘Simple Mode’ should be sufficient for most purposes. The left column shows the name of the service, the center column indicates its current status, and the right column gives a short description. For the selected service, a more detailed description is provided in the lower part of the window. To enable a service, select it in the table then select ‘Enable’. The same steps apply to disable a service.

Figure 13.1. YaST: Runlevel Editor

For detailed control over the runlevels in which a service is started or stopped or to change the default runlevel, first select ‘Expert Mode’. In this mode, the dialog displays the current default runlevel or “initdefault” (which is the runlevel into which the system boots by default) at the top. Normally, the default runlevel of a SUSE LINUX system is runlevel 5 (full multiuser mode with network and XDM). A suitable alternative might be runlevel 3 (full multiuser mode with network).

This YaST dialog allows the selection of one of the runlevels (as listed in Table 13.1. “Available Runlevels”) as the new default. Additionally use the table in this window to enable or disable individual services and daemons. The table lists the services and daemons available, tells whether they are currently enabled on your system, and, if so, for which runlevels. After selecting one of the rows with the mouse, click the check boxes representing the runlevels (‘B’, ‘0’, ‘1’, ‘2’, ‘3’, ‘5’, ‘6’, and ‘S’) to define the runlevels where the selected service or daemon should be running. Runlevel 4 is initially undefined to allow for the creation of a custom runlevel. Finally, a brief description of the currently selected service or daemon is provided just below the table overview.

With ‘Start, Stop, or Refresh’, decide whether a service should be activated. ‘Refresh status’ can be used to check the current status, if this has not been done automatically. ‘Set or Reset’ lets you select whether to apply your changes to the system or to restore the settings that existed before starting the runlevel editor. Selecting ‘Finish’ saves the changed settings to disk.

	Changing Runlevel Settings
Faulty runlevel settings may render a system unusable. Before applying your changes, make absolutely sure you know about their consequences.