论断一：vim
今天装了下正式版的RHEL7，发现熟悉的inittab中没有了修改默认运行级别，打开inittab以下服务器
[root@localhost init.d]# vi /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 /etc/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 set a default target, run:
#
# ln -sf /lib/systemd/system/<target name>.target /etc/systemd/system/default.targetide
中间没有了熟悉的 id:5:initdefaultip
RHEL7 使用systemd建立符号连接指向默认运行级别。get
修改方法为：
1.首先删除已经存在的符号连接
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rm /etc/systemd/system/default.target
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2.默认级别转换为3(文本模式)
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ln -sf /lib/systemd/system/multi-user.target /etc/systemd/system/default.target
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或者默认级别转换为5(图形模式)
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ln -sf /lib/systemd/system/graphical.target /etc/systemd/system/default.target
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3.重启
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reboot
-----------------------------------------------------------------------------it
论断二：class
Red Hat Enterprise Linux Server release 7.0 (Maipo) 修改启动级别
以前的配置文件在/etc/inittab 这里
vim /etc/inittab 咱们服务器用，习惯把id:5改为3，字符界面启动，或者最小化安装。
rhel7.0 作了不少大的改变，打开inittab看下
# inittab is no longer used when using systemd. /etc/inittab 这个文件已经再也不使用
# inittab is no longer used when using systemd.
#
# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# Ctrl-Alt-Delete is handled by /etc/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 相似于运行级别3
# graphical.target: analogous to runlevel 5 相似于运行级别5
#
# To set a default target, run: #运行下面 命令设置默认开机启动级别
#
# ln -sf /lib/systemd/system/<target name>.target /etc/systemd/system/default.target
/lib/systemd/system/ 里面有0-6 六个级别的文件软链接
runlevel0.target poweroff
runlevel1.target rescue
runlevel2.target multi-user
runlevel3.target multi-user
runlevel4.target multi-user
runlevel5.target graphical
runlevel6.target reboot
例如：修改5级别： ln -sf /lib/systemd/system/runlevel5.target /etc/systemd/system/default.target
例如：修改3级别： ln -sf /lib/systemd/system/runlevel3.target /etc/systemd/system/default.targetsed