Linux inittab configuration file

I. Declaration

The environment I am experimenting with is Centos 6.5.

Second, Introduction

In a Linux system, a program with a process number of 1 is a init,init process that is the starting point for all processes and manages all processes.

The init process invokes the/etc/inittab configuration file at run time, and the Inittab file describes several different init process runlevel levels.

Iii. contents of the document

# Inittab is only used by upstart for the default runlevel.## ADDING other Configur ATION here'll has NO EFFECT on YOUR system.## SYSTEM initialization is started by/etc/init/rcs.conf## individual Runle  Vels started by/etc/init/rc.conf## ctrl-alt-delete is handled by/etc/init/control-alt-delete.conf## Terminal Gettys is handled by/etc/init/tty.conf and/etc/init/serial.conf,# with the configuration in/etc/sysconfig/init.## for Informatio  n on what to write upstart event handlers, or how# upstart works, see Init (5), init (8), and Initctl (8). # # Default RunLevel. The runlevels used are:# 0-halt (do not set Initdefault to this) # 1-single user mode# 2-multiuser, without NF  S (the same as 3, if you don't have networking) # 3-full multiuser mode# 4-unused# 5-x11# 6-reboot Set Initdefault to this) # Id:5:initdefault: 

From the contents of the file, you can find a total of 6 different runlevel (runlevel) and specify the different levels of the INIT process to run with a command similar to Id:5:initdefault:.

Four, the function

Below is a detailed description of the effects at different levels:

The 0-init process shuts down all processes and terminates the system.

1-Switch the system to single-user mode and allow only administrators to enter.

2-Enables the system to enter multi-user mode, but cannot share files on the network. (This is the same as pattern 3 in the absence of network scenarios)

3-Complete multi-user mode, most commonly used.

4-rarely used.

5-Use X winsows terminal (graphical interface).

6-Close all processes and restart the system.

How to switch the system from graphical interface mode to command line mode:

Change Id:5:initdefault: To Id:3:initdefault:.

Linux inittab configuration file