trial and errored the python thing

2015/01/31/arbitrary_python_versions_on_flip.rst

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+Arbitrary Python versions on Flip
+=================================
+
+A question in the ``#osu-lug`` channel about running python 2.7 on a school
+server (which only has python 2.6.6) made me realize I should know how to do
+that but have never tried it.  `Stackoverflow`_ provides instructions for
+solving a similar problem, so I'm testing them out to make sure they work for
+Python 2.7.7 and Python 3.
+
+.. more::
+
+The Setup
+---------
+
+At Oregon State University, students in the engineering department have access
+to a trio of servers which, for most purposes, are interchangeable. If you're
+running a screen session for IRC, it's important to log in to the same flip
+(``flip1.engr.oregonstate.edu``, ``flip2.engr.oregonstate.edu``, or
+``flip3.engr.oregonstate.edu``) every time because the session exists in that
+particular server's memory. If you only care about stuff stored to disk, you
+can just ssh to ``flip.engr.oregonstate.edu`` to be round-robined onto an
+available server. Your NFS home directory is shared between all the flip
+servers, which is why the same files are also available whenever you log in
+with your engineering account to a Windows, Linux, or Mac computer in the
+university's computer.
+
+All 3 flips are identical; I happen to be on flip1 at the start of this
+tutorial::
+
+    -bash-4.1$ hostname
+    flip1.engr.oregonstate.edu
+
+It's running CentOS 6.6 and has Python 2.6.6 and Virtualenv 1.10.1 installed::
+
+    $ python --version
+    Python 2.6.6
+    $ virtualenv --version
+    1.10.1
+    $ cat /etc/redhat-release
+    CentOS release 6.6 (Final)
+
+**tl;dr:** Just ``ssh`` to ``youronid@flip.engr.oregonstate.edu``. You only
+need to specify flip{1-3} if you're doing IRC stuff.
+
+Install Python locally
+---------------------
+
+On Flip, run the following commands::
+
+    wget http://www.python.org/ftp/python/2.7.7/Python-2.7.7.tgz
+    tar -zxvf Python-2.7.7.tgz
+
+    # then you wait. it may take a few minutes.
+
+    cd Python-2.7.7
+    mkdir ~/python27
+
+    # all 3 of the following steps may take awhile.
+    ./configure --prefix=$HOME/python27
+    make
+    make install
+
+Use Python2.7.7
+---------------
+
+Instead of invoking ``python`` and getting the old version from your path,
+specify which python you want to run your program with::
+
+    ~/python27/bin/python my_awesome_file.py
+
+Or Make a Virtualenv
+--------------------
+
+::
+
+    $ virtualenv -p ~/python27/bin/python venv27
+    $ source venv27/bin/activate
+
+    (venv27)-bash-4.1$ python --version
+    Python 2.7.7
+
+
+Errors
+------
+
+If you get a permission denied error, check that files actually ended up in
+your ~/python27 directory. If the directory is empty, run ``make; make
+install`` in your Python-2.7.7 directory.
+
+Re-installing solved the failure-to-install issue for me.
+
+Trying it with Python 3, too
+============================
+
+Repeating the same process with Python 3.4.2 yields the error::
+
+    ImportError: No module named '_collections_abc'
+    ERROR: The executable venv3/bin/python3 is not functioning
+    ERROR: It thinks sys.prefix is '/nfs/stak/students/d/dunhame' (should be '/nfs/stak/students/d/dunhame/venv3')
+    ERROR: virtualenv is not compatible with this system or executable
+
+So, Flip's virtualenv version is too old. Fortunately, Python3 shipped with
+pyvenv::
+
+    $ python3/bin/pyvenv-3.4 venv3
+    $ source venv3/bin/activate
+    (venv3)$ python --version
+    Python 3.4.2
+
+For anyone who wants to copy and paste, the commands for installing Python
+3.4.2 are::
+
+    wget https://www.python.org/ftp/python/3.4.2/Python-3.4.2.tgz
+    tar -zxvf Python-3.4.2.tgz
+    cd Python-3.4.2
+    mkdir ~/python3
+    ./configure --prefix=$HOME/python3
+    make
+    make install
+
+.. _Stackoverflow: http://stackoverflow.com/questions/1534210/use-different-python-version-with-virtualenv
+.. author:: default
+.. categories:: none
+.. tags:: school
+.. comments::