CentOS7.7以及之后的版本不用执行，之前版本需要安装一个这个repo库。提供一些较新的软件版本（包含Python3）
yum install https://repo.ius.io/ius-release-el$(rpm -E '%{rhel}').rpm
安装Python3
yum install python3 -y
# cd /usr/bin/ # ll |grep python -rwxr-xr-x 1 root root 11232 Oct 2 2020 abrt-action-analyze-python lrwxrwxrwx 1 root root 9 May 1 13:08 python -> python3.6 lrwxrwxrwx 1 root root 9 Oct 30 2021 python2 -> python2.7 -rwxr-xr-x 1 root root 7144 Nov 17 2020 python2.7 lrwxrwxrwx 1 root root 9 Oct 7 2021 python3 -> python3.6 -rwxr-xr-x 2 root root 11328 Nov 17 2020 python3.6 -rwxr-xr-x 2 root root 11328 Nov 17 2020 python3.6m