centos 7修改默認運行級別

查看當前的運行級別

編輯文件：

vim /etc/inittab

# inittab is no longer used when using systemd.
#
# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
#
# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
#
# multi-user.target: analogous to runlevel 3
# graphical.target: analogous to runlevel 5
#
# To view current default target, run:
# systemctl get-default
#
# To set a default target, run:
# systemctl set-default TARGET.target

通過文件，可以瞭解到，centos7有兩種運行級別：
3：multi-user.target
5：graphical.target
查看當前的運行級別：systemctl get-default 命令
設置默認的啓動級別：systemctl set-default TARGET.target

[root@localhost ~]# systemctl get-default
graphical.target
[root@localhost ~]# 

graphical.target表示當前的運行級別是圖形界面。

設置默認的運行級別爲mulit-user

[root@localhost ~]# systemctl set-default multi-user.target
Removed symlink /etc/systemd/system/default.target.
Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/multi-user.target.
[root@localhost ~]# systemctl get-default
multi-user.target
[root@localhost ~]# 

通過systemctl get-default查看到當前的運行級別爲：multi-user.target，該命令重啓以後生效。

切換當前的運行級別

systemctl isolate multi-user.target
systemctl isolate graphical.target

在不重啓的情況下，切換運行級別