Linux entry-based system operating level 02

Linux has 7 levels of operation

1.init0 shut down the machine
2.init1 Single User (password missing profile modification error)
3.init2 full level of No network NFS
4.INIT3 Multi-user multi-CPU command line mode
5.INIT4 not used, reserved
6.init5 graphical interface
7.INIT6 restart

Related commands:

RunLevel viewing run Levels

[[email protected] ~]# runlevelN 3

N represents the previous run level
3 represents the current run level

Init N switch Run level
N indicates the level to toggle (both temporary switchover, restart failure)
Special Note: Cannot switch directly to single user mode can be switched before 3-5 (if the graphical system interface is already installed)

Linux everything is file (modify the configuration file for permanent effect)
Configuration file Storage Path/etc/inittab

[[email protected] ~]# vi /etc/inittab······# multi-user.target: analogous to runlevel 3# graphical.target: analogous to runlevel 5#//查看系统默认启动运行级别# To view current default target, run:修改默认启动级别（永久）# systemctl get-default## To set a default target, run:# systemctl set-default TARGET.target

For example, switch to the graphical interface:
[[email protected] ~]# systemctl get-default graphical.target
Then the restart takes effect

Linux entry-based system operating level 02