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How to change the default run level of a RedHat 9.0 or Fedora Core Linux system


During the boot process for Redhat 9.0 and Fedora Core systems the init command opens the /etc/inittab file to decide what "runlevel" the system should be booted to. The /etc/inittab file is a plain text file that can be opened with your favorite text editor.

The relavent section of a sample /etc/inittab file is as follows:

# Default runlevel. The runlevels used by RHS are:
#   0 - halt (Do NOT set initdefault to this)
#   1 - Single user mode
#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
#   3 - Full multiuser mode
#   4 - unused
#   5 - X11
#   6 - reboot (Do NOT set initdefault to this)
#
id:3:initdefault:

The key line in the example above is:

id:3:initdefault:

This tells the init process that the default run level for the system is run level 3. To change to a different run level simply change the number and save the /etc/inittab file. Before doing this, however, be absolutely sure you know which run level you want. Selecting the wrong runlevel can have serious consequences. To help with this a detailed description of the individual run levels is outlined in the table below:

Table 1: Linux Runlevel Descriptions
Runlevel
Runlevel Description
Runlevel 0
The halt runlevel - this is the runlevel at which the system shuts down. For obvious reasons it is unlikely you would want this as your default runlevel.
Runlevel 1
Single runlevel. This causes the system to start up in a single user mode under which only the root user can log in. In this mode the system does not start any networking or X windowing, X or multi-user services. This run level is ideal for system administrators to perform system maintenance or repair activities.
Runlevel 2
Boots the system into a multi-user mode with text based console login capability. This runlevel does not, however, start the network.
Runlevel 3
Similar to runlevel 2 except that networking services are started. This is the most common runlevel for server based systems that do not require any kind of graphical desktop environment.
Runlevel 4
Undefined runlevel. This runlevel can be configured to provide a custom boot state.
Runlevel 5
Boots the system into a networked, multi-user state with X Window System capability. By default the graphical desktop environment will start at the end of the boot process. This is the most common run level for desktop or workstation use.
Runlevel 6
Reboots the system. Another runlevel that you are unlikely to want as your default.

 
 
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