CentOS 7 默認的python版本是python2.7.5。因為yum依賴於默認的python版本的緣由，所以要先保留默認版本，並修改yum文件頭部后，才能開始安裝更新python2和python3兩個最新版本。（python2和python3共存）
一. 保留默認python版本2.7.5，並修改yum頭部，保持yum對默認版本python2.7.5的依賴
1.su root # 獲取root權限
2.mv /usr/bin/python2.7 /usr/bin/python2.7.5 # 保留默認版本python為python2.7.5
ln -s /usr/bin/python2.7.5 /usr/local/bin/python2.7.5 # 創建軟連接
3.ll /usr/bin/yum* # 查看/usr/bin/目錄下所有yum文件（7個）頭部
4.vi /usr/bin/yum* # 修改/usr/bin/目錄下所有yum文件（7個）頭部
#!/usr/bin/python —> #!/usr/bin/python2.7.5
5.vi /usr/libexec/urlgrabber-ext-down # 修改/usr/libexec/目錄下 urlgrabber-ext-down頭部
#!/usr/bin/python —> #!/usr/bin/python2.7.5
二. 安裝最新版python2.7.13和python3.6.2（python2和python3共存，修改后默認版本為python3.6.2）
准備工作：
1. 安裝wget命令（可以在線下載安裝包的命令）
yum -y install wget
2. 准備編譯環境
yum groupinstall 'Development Tools'
yum install zlib-devel bzip2-devel openssl-devel ncurses-devel
3. 下載並安裝最新版本的python2和python3的tgz壓縮文件
https://www.python.org/ftp/python/2.7.13/Python-2.7.13.tgz
https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tgz
開始安裝：
1. 進入下載目錄：
cd /usr/local/src
2. 下載並安裝最新版本python2：
wget https://www.python.org/ftp/python/2.7.13/Python-2.7.13.tgz
tar zxvf Python-2.7.13.tgz
cd Python-2.7.13
./configure
make all
make install
make clean
make distclean
rm -rf /usr/bin/python
rm -rf /usr/bin/python2
rm -rf /usr/bin/python2.7
ln -s /usr/local/bin/python2.7 /usr/bin/python
ln -s /usr/local/bin/python2.7 /usr/bin/python2
ln -s /usr/local/bin/python2.7 /usr/bin/python2.7
/usr/bin/python -V
/usr/bin/python2 -V
/usr/bin/python2.7 -V
rm -rf /usr/local/bin/python
rm -rf /usr/local/bin/python2
ln -s /usr/local/bin/python2.7 /usr/local/bin/python
ln -s /usr/local/bin/python2.7 /usr/local/bin/python2
python -V
python2 -V
python2.7 -V
3. 下載並安裝最新版本python3：
wget https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tgz
tar zxvf Python-3.6.2.tgz
cd Python-3.6.2
./configure
make all
make install
make clean
make distclean
rm -rf /usr/bin/python
rm -rf /usr/bin/python3
rm -rf /usr/bin/python3.6
ln -s /usr/local/bin/python3.6 /usr/bin/python
ln -s /usr/local/bin/python3.6 /usr/bin/python3
ln -s /usr/local/bin/python3.6 /usr/bin/python3.6
/usr/bin/python -V
/usr/bin/python3 -V
/usr/bin/python3.6 -V
rm -rf /usr/local/bin/python
rm -rf /usr/local/bin/python3
ln -s /usr/local/bin/python3.6 /usr/local/bin/python
ln -s /usr/local/bin/python3.6 /usr/local/bin/python3
python -V
python3 -V
python3.6 -V