Linux Run Level

(1) View Run level command description:

#Runlevel to view the levels that are running

#Who –r view the current level of the run and the level of the last run

9.5-2.1 can see that switching between different levels and then running commands to see different effects:

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Centos 5

Linux the run-level configuration file path is: /etc/inittab under

9.5-2.2 as shown:

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where the * * * part is Action and the corresponding Process

Id:runlevel:action:process which Process can hide

Action :

Wait : Wait Switch to this level to run one time

respawn : etc. Process stop, wait to start again

Initdefault : Sets the default level, Process omitted

Sysinit : Specify /etc/rc.d/rc.sysinit

(2) ID : 3 : Initdefault :

Si::sysinit:/etc/rc.d/rc.sysnit System Initialization tool, activating swap partition, etc.

L0:0:WAIT:/ETC/RC.D/RC.SYSINIT/RC 0

....

L6:6AIT:/ETC/RC.D/RC.SYSINIT/RC 6

Description rc0-6 The run level means reading /etc/rc.d/rc.0.d/ All Files

k* k##* off State The smaller the number, the more it runs and usually relies on other services

s* s##* Open State The smaller the number, the more running, the service that is dependent on

two digits ##/etc/rc.d/init.d/ Display under directory

For SRV in/etc/rc.d/rc0.d/k*;d o

$srv stop

Done

For SRV in/etc/rc.d/rc0.d/s*;d o

$srv start

Done

To view different types of links under different levels:

#ls/etc/rc.d #ls/ETC/RC.D/RC #ls/etc/rc.d/rc/rc0.d

9.5-2.3 as shown:

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middle section is the link type 0-6 9.5-2.4 and 9.5-2.5 show: command is #ls/etc/rc.d/rc3.d  which * S10network is open The latter is *k90network off state, chkconfig command view adjustment link open close

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( 3 ) Chkconfig command,

Add:

Sysv service scripts are placed in the /etc/rc.d/init.d (/ETC/INIT.D)

First create:

#!/bin/bash

#
#chkconfig: LLL ( number ) nn (number after S ) nn ( number of K )

Add again #Chkconfig –add name

Delete: Chkconfig–del name

#Chkconfig--level

#Chkconfig –list

( 4 ) #ls/etc/rc.d/rc.sysinit viewing system initialization Scripts

a , set host name

b , set Welcome information

C , activate Udev and the SELinux

D , Mount /etc/fstab File system defined in the file

e , interval root file system, and re-mount the root filesystem in read-write mode

F , set the system clock,

g , activate Swap Equipment

h , according to /etc/sysctl.conf file Set kernel parameters

I , activate LVM and Software RAID Equipment

J , load drivers for additional devices

k , Cleanup operations

/sbin/init à (/etc/inittab) à Set Run Level à run the system initialization script à Close or open the appropriate service à Login

CentOS 6

Init The program is: Upstart , configuration Files /etc/inittab , /etc/init/*.conf

#cd/etc/init

#ls rc.conf Running the service

#ls rcs.conf Startup Scripts   

9.5-2.6 as shown:

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Linux Run Level