在linux环境上安装python3.6.2程序.
到官网下载源码包安装：
安装python3.6.2的系统依赖包：
yun -y install zlib*
解压安装包：
tar -xvf Python-3.6.2.tar
进入安装目录：
cd Python-3.6.2
添加配置，指定安装位置：
./configure --prefix=/usr/local/python
编译源码并执行安装：
make && make install
到安装路径下验证安装是否成功：
[root@localhost bin]# pwd
/usr/local/python/bin
[root@localhost bin]# ./python3.6
Python 3.6.2 (default, Sep 8 2017, 11:30:01)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-18)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> print("hello world")
hello world
系统默认python版本为2.6（与python3.0以上不兼容）
[root@localhost ~]# which python
/usr/bin/python
[root@localhost ~]# python
Python 2.6.6 (r266:84292, Aug 18 2016, 15:13:37)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-17)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
将系统默认的python2.6移除，以方便后继所有python程序，默认使用python3
[root@localhost bin]# which python
/usr/bin/python
[root@localhost bin]# mv /usr/bin/python /usr/bin/python.bak
[root@localhost bin]# ln -s /usr/local/python/bin/python3.6 /usr/bin/python
[root@localhost bin]# python
Python 3.6.2 (default, Sep 8 2017, 11:30:01) #此时系统python已经替换为3.6
[GCC 4.4.7 20120313 (Red Hat 4.4.7-18)] on linux
Type "help", "copyright", "credits" or "license" for more information.
系统有两个python版本，2.6和3.6，分别写一个hello world 的脚本。
python2.6:
#!/usr/bin/python2.6
print 'hello world!'
python3.6:
#!/usr/bin/python
print 'hello world!'
分别成功执行，如下：
[root@localhost py]# ./py2.6-hello.py
hello world
[root@localhost py]# ./py3.6-hello.py
File "./py3.6-hello.py", line 2
print 'hello world!'
^
SyntaxError: Missing parentheses in call to 'print'
因为py3.6-hello.py是一个python2的语法，此时我们只需要将头部声音改为python2.6就可正常运行。
