Two versions of python on linux. how to make 2.7 the default
I've got two versions of python on my linuxbox:
$python
Python 2.6.6 (r266:84292, Jul 10 2013, 22:48:45)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
$ /usr/local/bin/python2.7
Python 2.7.3 (default, Oct 8 2013, 15:53:09)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
$ which python
/usr/bin/python
$ ls -al /usr/bin/python
-rwxr-xr-x. 2 root root 4864 Jul 10 22:49 /usr/bin/python
How can I make 2.7 be the default version so when I type python it puts me in 2.7?
Answer
You probably don't actually want to change your default Python.
Your distro installed a standard system Python in /usr/bin, and may have scripts that depend on this being present, and selected by #! /usr/bin/env python. You can usually get away with running Python 2.6 scripts in 2.7, but do you want to risk it?
On top of that, monkeying with /usr/bin can break your package manager's ability to manage packages. And changing the order of directories in your PATH will affect a lot of other things besides Python. (In fact, it's more common to have /usr/local/bin ahead of /usr/bin, and it may be what you actually want—but if you have it the other way around, presumably there's a good reason for that.)
But you don't need to change your default Python to get the system to run 2.7 when you type python.
First, you can set up a shell alias:
alias python=/usr/local/bin/python2.7
Type that at a prompt, or put it in your ~/.bashrc if you want the change to be persistent, and now when you type python it runs your chosen 2.7, but when some program on your system tries to run a script with /usr/bin/env python it runs the standard 2.6.
Alternatively, just create a virtual environment out of your 2.7 (or separate venvs for different projects), and do your work inside the venv.