I'm doing an altinstall of Python 2.7.13 on RHEL7 which has 2.7.5 installed. Here's how I'm building from source:
$ ./configure --prefix=/usr/local --enable-shared
$ make && sudo make altinstall
However, even when I tried to access this altinstall directly, I'm getting the system Python, rather than the altinstall. I've put SELinux into permissive mode and get the same result.
$ /usr/local/bin/python2.7 -V
Python 2.7.5
$ getenforce
Permissive
and when I enter the interpreter
$ /usr/local/bin/python2.7
Python 2.7.5 (default, Aug 2 2016, 04:20:16)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
I'm at a loss here. From everything I've been reading this should work. The only thing I can think of is that since they're both 2.7.X there's some sort of conflict, but I thought that was the reason for altinstalls in the first place.
I believe you're running into the same problem as in this thread: Strange Python compilation results with “--enable-shared” flag.
To fix it, you need to use:
LD_RUN_PATH=/usr/local/lib make && sudo make altinstall
(So that the generated binary looks for the correct shared Python library.)
As a sidenote, I think you'd be much better served by Red Hat Software Collections when you need to have different Python versions on one system. Check out About RHSCL.