問題解決：Centos7掛起重開無IP的問題风范，不必每次都重新設置network
使用vim修改配置文件
vim /etc/sysconfig/network-scripts/ifcfg-ens33
將最下方的ONBOOT=no改為yes
保存退出
再輸入service network restart 再重啟網(wǎng)絡就解決了
實驗一：修改centos7的網(wǎng)卡名稱
1）終端下輸入命令gedit /boot/grub2/grub.cfg進入圖形編輯界面
linux16 后加 net.ifnames=0
最后
reboot重啟一下就可以了2）使用vim命令修改
最后
reboot重啟
實驗二：時間同步
ntpdate 172.16.0.1
nano /etc/ntp.conf
server 172.16.0.1 iburst
service ntpd start centos6
systemctl start ntpd centos7
實驗三：screen——建立會話
一個主機，兩個終端
lsblk
rpm -ivh /run/media/root/CentOS\ 7\ x86_64/Packages/screen-4.1.0-0.23.20120314git3c2946.el7_2.x86_64.rpm
A: screen -S help
B: screen -ls
screen -x help
exit
實驗四：更改Centos 6開機運行級別為命令行界面
vim /etc/inittab
# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# System initialization is started by /etc/init/rcS.conf
#
# Individual runlevels are started by /etc/init/rc.conf
#
# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
#
# Terminal gettys are handled by /etc/init/tty.conf 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 do not have networking)
# 3 - Full multiuser mode
# 4 - unused
# 5 - X11
# 6 - reboot (Do NOT set initdefault to this)
#
id:5:initdefault: #將此處的數(shù)字改為3即可
"/etc/inittab" 26L, 884C
點擊i ,編輯vim文件，然后Esc鍵退出編輯 赦肃，冒號：+ w鍵寫入 、再冒號：+ q鍵退出
實驗五：更改Centos7下的運行級別
systemctl isolate multi-user.target
systemctl isolate runlevel3.target //作用與上面相同
或者
systemctl isolate graphical.target
systemctl isolate runlevel5.target //作用與上面相同
上面的的命令是暫時的更改，要想開機后默認運行命令行界面：
第一步：rm /etc/systemd/system/default.target //刪除默認的開機運行文件
第二步：
1 ln -sf /lib/systemd/system/multi-user.target /etc/systemd/system/default.target
2 ln -sf /lib/systemd/system/runlevel3.target /etc/systemd/system/default.target
3 sytemctl set-default multi-user.target
上面3個命令任選其一即可。
