参考这个文章
https://www.cnblogs.com/Jesuca/archive/2012/02/24/2366940.html
主要有几个命令： 列出来有几个屏幕 xrandr --listmonitors
列出来接口 xrandr | grep " connected " | awk '{ print$1 }' 找里面的conected xrandr

如果确实已经检测到2个显示器了，那就扩展一下就行了，如下命令：(你自己的左右就是左右方向)
xrandr --output DisplayPort-1-3 --auto --left-of HDMI-1
（具体参数参考下面的，HDM 是我正在显示的显示器，在他左边放了一个）
[root@localhost X11]# xrandr Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384
HDMI-1 connected primary 1920x1080+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm
1920x1080 60.00*+ 74.97 50.00 59.94
1920x1080i 60.00 50.00 59.94
......
......
......
DisplayPort-1-3 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm
1920x1080 60.00*+
1600x900 60.00

https://linux.cn/article-9586-1.html
详见以上网址，好用的是way 1

cat /etc/os-release （可以看发行版本号）

Way 1
lsb_release -a

Way 2

uname -r 或 cat /proc/version

启动： systemctl start firewalld
查看状态： systemctl status firewalld
禁用，禁止开机启动： systemctl disable firewalld
停止运行： systemctl stop firewalld
https://www.cnblogs.com/leoxuan/p/8275343.html#:~:text=CentOS7%20%EE%80%80%E9%98%B2%E7%81%AB%E5%A2%99%EE%80%81%EF%BC%88%EE%80%80firewall%EE%80%81%EF%BC%89%E7%9A%84%E6%93%8D%E4%BD%9C%EE%80%80%E5%91%BD%E4%BB%A4%EE%80%81%20%E5%AE%89%E8%A3%85%EF%BC%9Ayum%20install%20firewalld%201%E3%80%81firewalld%E7%9A%84%E5%9F%BA%E6%9C%AC%E4%BD%BF%E7%94%A8%20%E5%90%AF%E5%8A%A8%EF%BC%9A,systemctl%20start%20firewalld%20%E6%9F%A5%203.%E4%BF%A1%E4%BB%BB%E7%BA%A7%E5%88%AB%EF%BC%8C%E9%80%9A%E8%BF%87Zone%E7%9A%84%E5%80%BC%E6%8C%87%E5%AE%9A%20drop%3A%20%E4%B8%A2%E5%BC%83%E6%89%80%E6%9C%89%E8%BF%9B%E5%85%A5%E7%9A%84%E5%8C%85%EF%BC%8C%E8%80%8C%E4%B8%8D%E7%BB%99%E5%87%BA%E4%BB%BB%E4%BD%95%E5%93%8D%E5%BA%94

https://blog.csdn.net/weixin_43046653/article/details/105583100
alsamixer，打开可视化，依次滚动鼠标滚轮，修改每一个的音量的上下，没有再F6选择声卡。

用grep 方法：grep -n scaler ./
find ./ -name st.cmd.acr grep -r "asyn=/opt/asyn-t56-77" /path/to/search/directory grep -r --include "*.txt" "asyn=/opt/asyn-t56-77" /path/to/search/directory

RH 系可以用yum groupinstall "Development Tools" "Development Libraries"，但我实际操作，Libraries不可以用； yum groupinstall "Additional Development" 可用； 具体可用yum grouplist 列出来