1.ssh配置免访问文件：authorized_keys
2.apt设置临时代理：
sudo apt-get -o Acquire::http::proxy="socks5h://192.168.0.102:7890/" install mariadb-server
3.CentOS7 升级GCC
(3.1) rpm -q gcc
(3.2) rpm -e [第二步查到的版本号]
如果
error: Failed dependencies:
    gcc = 4.4.7-23.el6 is needed by (installed) gcc-c++-4.4.7-23.el6.x86_64
    gcc = 4.4.4 is needed by (installed) libtool-2.2.6-15.5.el6.x86_64
rpm -e gcc-c++-4.4.7-23.el6.x86_64
rpm -e libtool-2.2.6-15.5.el6.x86_64
验证卸载：
[root@123 /]# gcc -v
-bash: /usr/bin/gcc: No such file or directory
[root@123 /]# g++ -v
-bash: /usr/bin/g++: No such file or directory
yum install centos-release-scl
yum install -y devtoolset-11-gcc devtoolset-11-gcc-c++
scl enable devtoolset-11 bash
vim /etc/profile
PATH=$PATH::/opt/rh/devtoolset-11/root/usr/bin