CentOS 7 RunLevel Switch

Versions prior to CentOS 7 are defined by the/etc/inittab file to define the system RunLevel:

[[email protected] ~]$ cat/etc/centos-release CentOS release 6.4 (Final) [[email protected] ~]$ cat/etc/ Inittab # Inittab is a used by upstart for the default runlevel.## ADDING other CONFIGURATION here would have NO EFFECT On YOUR system.## SYSTEM initialization was started by/etc/init/rcs.conf## individual runlevels are started by/etc/init/r c.conf## Ctrl-alt-delete is handled by/etc/init/control-alt-delete.conf## Terminal gettys be handled by/etc/init/tty.c  onf and/etc/init/serial.conf,# with configuration in/etc/sysconfig/init.## for information on how 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 NFS (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:3:initdefault:[[email protecTed] ~]$  

The CentOS 7 version no longer uses this file to define the system RunLevel, and the associated run-level settings are invalid:

[Email protected] etc]$ cat/etc/centos-release centos Linux release 7.0.1406 (Core) [[email protected] etc]$ cat/etc/in Ittab # Inittab is no longer used if using systemd.## ADDING CONFIGURATION here'll has no EFFECT on YOUR system.## Ct Rl-alt-delete is handled by/etc/systemd/system/ctrl-alt-del.target## SYSTEMD uses ' targets ' instead of runlevels. By default, there is both main targets:## multi-user.target:analogous to RunLevel 3# graphical.target:analogous to Runle Vel 5## to set a default target, run:## ln-sf/lib/systemd/system/<target Name>.target/etc/systemd/system/default. Target#id:3:initdefault:  

The new version of the runlevel is defined under/lib/systemd/system:

[Email protected] system]$ ls-ltr/lib/systemd/system/runlevel*lrwxrwxrwx. 1 root root 13 July  14:22/lib/systemd/system/runlevel1.target-rescue.targetlrwxrwxrwx. 1 root root 15 July  3 0 14:22/lib/systemd/system/runlevel0.target, poweroff.targetlrwxrwxrwx. 1 root root 17 July  14:22/lib/systemd/system/runlevel2.target-multi-user.targetlrwxrwxrwx. 1 root root 17 July 
   30 14:22/lib/systemd/system/runlevel3.target, multi-user.targetlrwxrwxrwx. 1 root root 17 July  14:22/lib/systemd/system/runlevel4.target-multi-user.targetlrwxrwxrwx. 1 root root 16 July 
   30 14:22/lib/systemd/system/runlevel5.target, graphical.targetlrwxrwxrwx. 1 root root 13 July  14:22/lib/systemd/system/runlevel6.target-Reboot.target

You can set different runlevel for different needs:
If you set a command-line-level method:

Ln-sf/lib/systemd/system/runlevel3.target/etc/systemd/system/default.target
Or
Ln-sf/lib/systemd/system/multi-user.target/etc/systemd/system/default.target
Or
Systemctl Set-default Multi-user.target

To set the window-level method:

Ln-sf/lib/systemd/system/runlevel5.target/etc/systemd/system/default.target or ln-sf/lib/systemd/system/ Graphical.target/etc/systemd/system/default.target
Or
Systemctl Set-default Graphical.target

CentOS 7 RunLevel Switch