RHEL6：将Python切换回原始默认版本

Question

I am using RHEL6 which came with Python 2.6.6 pre-installed on it as the default python executable.

Some months ago, I installed Python 2.7 on it and switched the default python version to 2.7 (yes, idiot move I now realize). So now when I type python it runs Python 2.7.

Also: which python gives me /usr/local/bin/python

As you might expect, and I only found out recently, this has caused issues when trying to run some system scripts which depend on the version being 2.6. The 2.6 installation still exists and I can run it by either python2 or python2.6 .

Also: which python2 gives /usr/bin/python2 and which python2.6 gives /usr/bin/python2.6

The problem is that I do not remember how I switched the default version to 2.7. I know I didn't create any alias, because I can't find any in the ~/.bashrc file.

Does anyone have any advice on how I can revert back by changes so that Python 2.6.6 becomes the default once again? I can provide any further information that might be necessary to analyze this problem. Moreover, I have a couple of other people around me who are also using RHEL6 and haven't played around with their python installations, so if I need to copy any original scripts from /usr/bin/ to get this fixed I can get it from them, as long as I know what to get.

Thanks in advance for any advice!

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Responses to Barun Sharma:

Running ls -l /usr/local/bin/python* gives me:

-rwxr-xr-x. 2 root root 6111394 Jan 16 2015 /usr/local/bin/python -rwxr-xr-x. 2 root root 6111394 Jan 16 2015 /usr/local/bin/python2.7 -rwxr-xr-x. 1 root root 1624 Jan 16 2015 /usr/local/bin/python2.7-config lrwxrwxrwx. 1 root root 9 Dec 26 2014 /usr/local/bin/python3 -> python3.4 -rwxr-xr-x. 2 root root 8777236 Dec 26 2014 /usr/local/bin/python3.4 lrwxrwxrwx. 1 root root 17 Dec 26 2014 /usr/local/bin/python3.4-config -> python3.4m-config -rwxr-xr-x. 2 root root 8777236 Dec 26 2014 /usr/local/bin/python3.4m -rwxr-xr-x. 1 root root 3013 Dec 26 2014 /usr/local/bin/python3.4m-config lrwxrwxrwx. 1 root root 16 Dec 26 2014 /usr/local/bin/python3-config -> python3.4-config lrwxrwxrwx. 1 root root 16 Jan 16 2015 /usr/local/bin/python-config -> python2.7-config

Answer 1

create a soft link:-

ln -s /usr/bin/python2 /usr/local/bin/python 

Or directly point /usr/local/bin/python to your python2.6 binary(ie where ~/usr/bin/python2` points).

Follow these steps:-

1) rm /usr/local/bin/python . This would remove the soft link. But python 2.7 will still be there. You can check /usr/local/bin/python2.7 .

2) ln -s /usr/local/bin/python2.6 /usr/local/bin/python . Symbolic link from python to python2.6

Also when you are working on python, I would advise you to use virtual environment and install your required python version and other packages. I generally do not install packages to system python when it is required for a specific project(rather do it on a virtual env).

Answer 2

Once you have your system back to normal, the way to add new versions of Python 2.7, 3.3, or 3.4 to RHEL (6 or 7) is to utilize Software Collections (aka RHSCL or SCL) which install along side the original Python versions. There are many other languages, databases, web servers, and other tools, too. RHSCLs are included in most RHEL subscriptions.

To get started: http://developers.redhat.com/products/softwarecollections/overview/

You can also find information here: https://access.redhat.com/products/Red_Hat_Enterprise_Linux/Developer/#rhscl=&dev-page=5

OR here: http://developerblog.redhat.com/tag/software-collections/