virtualenv如何创建不同的python环境？(How can virtualenv create different python environments?)

 我的服务器有3个virtualenv脚本： 
 
$ ls -lt virtual*
lrwxrwxrwx 1 root root  4 Nov 22 06:19 virtualbox -> VBox
-rwxr-xr-x 2 root root 55 Aug 14 19:34 virtualenv
-rwxr-xr-x 1 root root 55 Aug 14 19:34 virtualenv2
-rwxr-xr-x 2 root root 55 Aug 14 19:34 virtualenv3
$ cat virtualenv
#!/usr/bin/python3
import virtualenv
virtualenv.main()
$ cat virtualenv2
#!/usr/bin/python2
import virtualenv
virtualenv.main()
$ cat virtualenv3
#!/usr/bin/python3
import virtualenv
virtualenv.main()
 
 我知道virtualenv2用于创建Python 2环境，而virtualenv3用于Python 3 。 但令我困惑的是为什么只需将/usr/bin/python2修改为shebang行中的/usr/bin/python3就能达到创建不同环境的效果？ 它背后的魔力是什么？ 

My server has 3 virtualenv scripts: 
 
$ ls -lt virtual*
lrwxrwxrwx 1 root root  4 Nov 22 06:19 virtualbox -> VBox
-rwxr-xr-x 2 root root 55 Aug 14 19:34 virtualenv
-rwxr-xr-x 1 root root 55 Aug 14 19:34 virtualenv2
-rwxr-xr-x 2 root root 55 Aug 14 19:34 virtualenv3
$ cat virtualenv
#!/usr/bin/python3
import virtualenv
virtualenv.main()
$ cat virtualenv2
#!/usr/bin/python2
import virtualenv
virtualenv.main()
$ cat virtualenv3
#!/usr/bin/python3
import virtualenv
virtualenv.main()
 
I know virtualenv2 is used to create Python 2 environment while virtualenv3 is for Python 3. But what confuses me is why just modify the /usr/bin/python2 to /usr/bin/python3 in shebang line can achieve the effect that create different environments? What is the magic behind it? 

原文：https://stackoverflow.com/questions/41274579