1、查看python安装目录

whereis python

2、查看/usr/bin/目录下的python文件

ls -al /usr/bin/python*

3、安装python3相关的安装包，用于编译python3

yum install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gcc make -y

安装完成后的截图：

3.1、如果出现安装失败，提示找不到源，可以通过更换yum源解决，更新为阿里源。

3.1.1、修改yum源的文件

vi /etc/yum.repos.d/CentOS-Base.repo

3.1.2、把内容替换成阿里源的网址

# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#

[base]
name=CentOS-$releasever - Base - mirrors.aliyun.com
failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos/$releasever/os/$basearch/
        https://mirrors.aliyuncs.com/centos/$releasever/os/$basearch/
        https://mirrors.aliyun.com/centos$releasever/os/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#released updates
[updates]
name=CentOS-$releasever - Updates - mirrors.aliyun.com
failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
        https://mirrors.aliyuncs.com/centos/$releasever/updates/$basearch/
        https://mirrors.aliyun.com/centos$releasever/updates/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras - mirrors.aliyun.com
failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
        https://mirrors.aliyuncs.com/centos/$releasever/extras/$basearch/
        https://mirrors.aliyun.com/centos$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus - mirrors.aliyun.com
failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
        https://mirrors.aliyuncs.com/centos/$releasever/centosplus/$basearch/
        https://mirrors.aliyun.com/centos$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib - mirrors.aliyun.com
failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/
        https://mirrors.aliyuncs.com/centos/$releasever/contrib/$basearch/
        https://mirrors.aliyun.com/centos$releasever/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

3.1.3、清理源缓存

yum clean all

3.1.4、更新源缓存

yum makecache

3.1.5、再次执行安装命令

yum install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gcc make -y

4、安装pip

yum install python-pip -y

5、下载python3

写这个文档是，python最新版本是3.9.4版本，所以我安装的是3.9.4版本

wget https://www.python.org/ftp/python/3.9.4/Python-3.9.4.tar.xz

6、把python安装包移动到/home/tool目录

tool目录是我自己创建的目录，用途就是放置python3的安装包。

mv Python-3.9.4.tar.xz /home/tool/

7、解压python安装包

tar -xf Python-3.9.4.tar.xz

8、进入解压后的python目录

cd ./Python-3.9.4/

9、编译python3

./configure prefix=/usr/local/python3

10、在python3.9.4目录里，安装python3

make && make install

12、查看/usr/local/目录下是否有python3的文件，有则证明安装成功

ls -al /usr/local/

11、将之前的python软连接备份

mv /usr/bin/python /usr/bin/python.bak

12、添加新的软连接，把python3的软连接添加到python文件里

ln -s /usr/local/python3/bin/python3.9 /usr/bin/python

13、查看python版本号

python -V