WHAT’S RUNLEVELS AND HOW TO CONFIGURE RUNLEVELS IN LINUX

In this post you will learn about runlevels and how to configure runlevels in linux .

RUNLEVELS are the mode of operation in the computer operating system that defines the state of system after boot .

To view the runlevels of your linux system open the /etc/inittab through vim .

[root@dhcppc6 ~]# vim /etc/inittab
  • You will see here seven different types of runlevels . Default runlevel is set to 5  (graphical mode )  .
# inittab       This file describes how the INIT process should set up
#               the system in a certain run-level.
#
# Author:       Miquel van Smoorenburg, <miquels@drinkel.nl.mugnet.org>
#               Modified for RHS Linux by Marc Ewing and Donnie Barnes
#
# 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:5:initdefault:

# System initialization.
si::sysinit:/etc/rc.d/rc.sysinit
l0:0:wait:/etc/rc.d/rc 0
l1:1:wait:/etc/rc.d/rc 1
l2:2:wait:/etc/rc.d/rc 2
l3:3:wait:/etc/rc.d/rc 3
l4:4:wait:/etc/rc.d/rc 4
l5:5:wait:/etc/rc.d/rc 5
l6:6:wait:/etc/rc.d/rc 6
# Trap CTRL-ALT-DELETE
ca::ctrlaltdel:/sbin/shutdown -t3 -r now
# When our UPS tells us power has failed, assume we have a few minutes
# of power left.  Schedule a shutdown for 2 minutes from now.
# This does, of course, assume you have powerd installed and your
# UPS connected and working correctly.

Before we make any changes i suggest you to backup the runlevel file . Means if you make anything wrong in this file your system might not work properly .

[root@dhcppc6 ~]# cp /etc/inittab /etc/inittab.bak
  • To recover copy that backup file into main file .
[root@dhcppc6 ~]# cp /etc/inittab.bak /etc/inittab

THESE ARE THE SEVEN RUNLEVELS IN LINUX

ID Name Description
0 Halt System won’t be able to start . Pc will shutdown after boot .
1 Single-user mode This is basically  administration mode
2 Multi-user mode Its a command line mode where multi user can login .But does not configure network interfaces
3 Multi-user mode with networking Command line with network interface .
4 Not used/user-definable This ones is empty for special purpose .
5 Start the system normally with appropriate display manager (with GUI)  In this user can work in both graphical and command line mode .
6 Reboot This reboots system again and again

HOW TO CHANGE RUNLEVELS IN GRUB

  • First restart your system .

linux restart

 

  • When this screen appears ( BOOTING LINUX )press up and down arrow key .

redhat linux booting time

  • Now you are in Grub settings . Press e to edit before booting .

grub in linux

  • Now go to Kernel  and press ” e ” to edit this kernel .

grub in linux

  • Now you will see this type of screen .  Hit spacebar and enter numeric 1 .

grub in linux

grub in linux

  • Then Boot the kernel by pressing “ b ” .  We have entered ” 1 ” because we want to enter single user mode in linux .

grub in linux

  • Now we are in single user mode .

single usermode in linux

  • Now open runlevel file ( /etc/fstab ) through vim

single user mode in linux

  • Some users have problem in their system that reboots again and again because their id is 6   ( runlevel 6 )  . Just press ” I ” ( to enter the Insert mode ) . And in place of 6 , make id 5 ( runlevel 5 ) .Then press ESC and type : wq ( to save and quit )

single user mode in linux

  • IF you are using command line mode and want graphical mode in your system Change id to 5 . In place of 3 write 5 .

single user mode in linux

  • And if you want only command line mode , just write 3 in place of 5 . ID will be 3 .

single user mode in linux

  • Press Esc and type :wq ( to save and quit )  .
  • Then simply type reboot  ( to reboot the machine .)

single user mode in linux

 

WHAT’S STELNET AND HOW TO CONFIGURE STELNET IN LINUX AS SERVER AND WINDOWS OR ANDROID AS CLIENT

WHAT’S SCP – HOW TO DOWNLOAD/UPLOAD FILE OR FOLDER USING SCP COMMAND IN LINUX

HOW TO INSTALL WINDOWS SOFTWARE IN LINUX THROUGH CROSSOVER .

 

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