Re: [PLUG] Fixing a Python library mismatch

[JP Vossen via plug <plug@lists.phillylinux.org>]

On 5/20/20 1:22 PM, brent timothy saner via plug wrote:
> On 5/18/20 18:52, Fred Stluka via plug wrote:
> > On 5/16/20 4:14 PM, Walt Mankowski via plug wrote:
> > > I think both venv and pyvenv are more than I need most of the
> > > time.
> > Walt,
> >
> > Keep in mind that Python virtual environments are astonishingly
> > lightweight.  Much, much, much simpler than you might expect.
> > I dodged them for a little while, as one more complication that
> > I didn;t yet need.  Not true.  Really simple and really useful.  I
> > now use them for EVERY python project, no matter how small.

I love virtualenv, I don't install Ansible without it anymore, and that 
allows me to have a bunch of different versions when I need them.

Ansible is not what I'd call a light-weight venv (see example).  I don't 
care.  This is SO much simpler and easier than anything else!  KISS!

This is what I do:
1. Deactivate any existing virtenv: `deactivate`
2. Create a virtenv: `python -m virtualenv ~/venv/ansible-2.9.2`
3. Hack the prompt: `perl -i -pe 's/PS1="\(`basename 
\\"\$VIRTUAL_ENV\\"`\) ?\$PS1"/PS1="\\n(`basename 
\"\$VIRTUAL_ENV\"`)\$PS1"/;' ~/venv/ansible-2.9.2/bin/activate`
4. Activate the virtenv: `source ~/venv/ansible-2.9.2/bin/activate`
5. Install Ansible: `pip install ansible==2.9.2`

Note in step 2 you need to watch out for older distros because you might 
get Python2.  Experiment as needed.

<soap box>
My step 3 results in a pretty hairy prompt, but I like it that way 
because it's 100% self documenting.  YMMV.  Example below.

```
(ansible-2.9.2)
[root@drake:T1:L1:C5082:J0:2020-05-20_13:29:08_EDT]
/root/ansible# du -hsc ~/venv/*
65M	/root/venv/ansible-2.3.2.0.DEAD
75M	/root/venv/ansible-2.4.3.0.DEAD
90M	/root/venv/ansible-2.5.15
158M	/root/venv/ansible-2.9.2
387M	total
```
T1 = pTTY, L# = nesting level, C# = command number in history, J# = 
background job count.  And as long as I remember to hit an enter or 2 
before starting a new/long command, the consecutive prompt dates can 
give me elapsed time if I need it and forgot to use `time`.

I can't tell you how many times I've pulled stuff out of my scroll-back 
buffer, sometimes from *days* ago, to answer some question or add data 
to some ticket.  And *everything* is Just Right There.  Copy, paste, done.
</soap box>

Later,
JP
--  -------------------------------------------------------------------
JP Vossen, CISSP | http://www.jpsdomain.org/ | http://bashcookbook.com/
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