title: How to check all versions of python installed on osx and centos
body: <p>I just started setting up a centos server today and noticed that the default version of python on centos is set to 2.6.6. I want to use python 2.7 instead. I googled around and found that 2.6.6 is used by system tools such as YUM so I should not tamper with it. Then I opened up a terminal on my mac and found that I had python 2.6.8 and 2.7.5 and 3.3.3 installed. Sorry for the long story. In short I just want to know how to lookup all the version of python installed on centos so I don't accidentally install it twice.</p>