[Tutor] Wish to upgrade Python 3.6.5 to Python 3.6.6 for Linux Mint 19

[boB Stepp]

On Sat, Jul 14, 2018 at 8:23 PM Mats Wichmann <mats at wichmann.us> wrote:
>
> take a look at pyenv. should make it fairly easy.
>
> https://github.com/pyenv/pyenv

I just completed getting access to Python 3.6.6 using pyenv, so I
guess I'll post my experience for future searchers.  It was not
totally painless, and I am still pondering whether I used "sudo"
inappropriately or not.  Recall I am on Linux Mint 19 Cinnamon
edition.

First, the page Mats linked to mentioned an automatic installer for
pyenv in another GitHub project of the author's, so I used that.  It
was here:  https://github.com/pyenv/pyenv-installer

I used the recommended "GitHub way" instead of the PyPi way which
apparently is still in development and doesn't work for Python 3
anyway.  So I ran:

$ curl -L https://github.com/pyenv/pyenv-installer/raw/master/bin/pyenv-installer
| bash

Then I added to the end of my .bashrc:

export PATH="/home/bob/.pyenv/bin:$PATH"
eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"

This apparently allows pyenv's "shims" to take precedence in the
search path for Python versions.  Warning:  On the page Mats linked
there are some reports of getting into an infinite search loop if
these lines are added to .bashrc.  After pondering the specifics I did
not think it would affect me, so I went ahead with what I did.

I then did the suggested restart of my shell with:

$ exec "$SHELL"

pyenv seemed to be successfully installed.  I ran

$ pyenv update

just to be sure I had the latest, greatest, which I did.  I then ran

$pyenv install --list

to see if Python 3.6.6 was available.  It was and the list of
available versions is HUGE running from 2.1.3 to 3.8-dev to Active
Python versions to Anaconda versions, IronPython, Jython, MiniConda,
PyPy, Stackless, etc.  So I thought I was ready to download and
install Python 3.6.6 with

$ pyenv install 3.6.6

It *did* download from
https://www.python.org/ftp/python/3.6.6/Python-3.6.6.tar.xz, something
you could tell I was concerned about from my earlier posts.
Unfortunately I got:

Installing Python-3.6.6...

BUILD FAILED (LinuxMint 19 using python-build 20180424)

So I went to https://github.com/pyenv/pyenv/wiki/Common-build-problems,
which at the very top of the page recommended running this:

$ sudo apt-get install -y make build-essential libssl-dev zlib1g-dev
libbz2-dev \
libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \
xz-utils tk-dev libffi-dev

So without pausing for further thought I did run it, but now wonder if
this will cause me future consequences with system stuff as later I
read on the FAQ page a similar command without granting sudo
privileges.  So I jumped into the fire on this one without fully
understanding what I was doing.

But after doing this I was able to get 3.6.6, but there was still one
more thing to do and that was to run

$ pyenv global 3.6.6

because I did want to be able to type python3 in the shell and get
specifically 3.6.6 as my default version -- for now at least.

I probably did not do everything like I should, but maybe this will
help someone down the line do better.  So far I seem to have
everything working and doing what I had hoped for.  pyenv looks like a
fine tool for managing as many Python versions as one wants to play
around with, and does seem to support virtual environments with a
plugin.

boB