Python libs on Debian/Raspbian

Gary E. Miller gem at
Tue Dec 19 20:53:27 UTC 2017

Yo Richard!

On Tue, 19 Dec 2017 00:26:47 -0600
Richard Laager <rlaager at> wrote:

> On 12/18/2017 09:10 PM, Gary E. Miller via devel wrote:
> > On Fri, 8 Dec 2017 22:34:46 -0600
> > Richard Laager <rlaager at> wrote:  
> >> When you say PYTHONPATH, do you mean:
> >>
> >> 1) "a custom directory set in the environment variable PYTHONPATH"
> >> or
> >> 2) A directory that python searches.  
> > 
> > Hmm... I think those are the same.  
> Okay, that's what I thought you thought. This may be leading to some
> confusion for you, and it's definitely making your arguments hard to
> follow for me.

Yeah, constantly changing the terminology is confusing.

> They're definitely NOT the same.

I'm still listening...

> > How do you think they differ?  
> As I said:
> >> #1 is PYTHONPATH. #2 is sys.path, not PYTHONPATH.  

Yeah?  So?  And what do you mean by #1 and #2?  Context please?

> > Explain?  
> As I wrote (to you, CC devel) on 2017-12-12 in the other thread:

Sorry, I got sick, had to take some days off.  I'm still not caught up
on my backlog of email.

> ----
> sys.path is the path that is actually searched. sys.path is built
> See also the official docs:

Yeah, yeah, yeah, all boilerplate.  I understand all that.  The
point is?

>   The FHS says that user installed packages go in /usr/local. It is
> our understanding that upstream Python, when configured to install in
>   /usr, does not include anything from /usr/local in sys.path, though
>   some distros (e.g. Debian) patch this.

Uh, what?  Since when does upstream Python ever install anything NTPsec???

Not our problem.

> Given that, absent distro patching, it is *impossible* to both honor
> --prefix=/usr/local (i.e. never write anything outside of /usr/local)
> and have the modules loaded by default, without the user modifying
> sys.path (by either setting PYTHONPATH or creating a .pth file).

Yup, always beleived that, I agree 100%.  So what's the problem

> The suggestions on the other thread are to: A) warn the user,
> suggesting they create a .pth file, or B) create the .pth file for
> them, violating prefix, but minimally.

Yup, those, and a few more.  So, all that and back to last weeks
issue: which of those (including others you skipped) do we do.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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