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The original command python line

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  The original command python line Damjan Georgievski <gdamjan@gmail.com> - 2012-03-04 06:38 +0100
    Re: The original python command line Damjan Georgievski <gdamjan@gmail.com> - 2012-03-04 06:52 +0100
    Re: The original command python line Chris Rebert <clp2@rebertia.com> - 2012-03-03 21:48 -0800
      Re: The original command python line Grant Edwards <invalid@invalid.invalid> - 2012-03-04 14:34 +0000
    Re: The original command python line Chris Rebert <clp2@rebertia.com> - 2012-03-03 21:57 -0800
      Re: The original command python line Damjan Georgievski <gdamjan@gmail.com> - 2012-03-04 07:20 +0100
        Re: The original command python line Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-03-04 02:19 -0500

#21178 — The original command python line

How can I get the *really* original command line that started my python
interpreter?

Werkzeug has a WSGI server which reloads itself when files are changed
on disk. It uses `args = [sys.executable] + sys.argv` to kind of
recreate the command line, and the uses subprocess.call to run that
command line.

BUT that's problematic as, when you run::

	python -m mypackage --config

sys.argv printed in mypackage/__main__.py will be::

	['/full/path/to/mypackage/__main__.py', '--config']

so you get::

	python /full/path/to/mypackage/__main__.py --config

instead of::

	python -m mypackage --config


the difference in the 2 cases is what the current package is, and
whether you can use relative imports.


-- 
damjan

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#21179 — Re: The original python command line

> How can I get the *really* original command line that started my python
> interpreter?
> 
> Werkzeug has a WSGI server which reloads itself when files are changed
> on disk. It uses `args = [sys.executable] + sys.argv` to kind of
> recreate the command line, and the uses subprocess.call to run that
> command line.
> 
> BUT that's problematic as, when you run::
> 
> 	python -m mypackage --config
> 
> sys.argv printed in mypackage/__main__.py will be::
> 
> 	['/full/path/to/mypackage/__main__.py', '--config']
> 
> so you get::
> 
> 	python /full/path/to/mypackage/__main__.py --config
> 
> instead of::
> 
> 	python -m mypackage --config
> 
> 
> the difference in the 2 cases is what the current package is, and
> whether you can use relative imports.

BTW, the same thing happens in Python 3.2.2. To reproduce::

mkdir /tmp/X
cd /tmp/X

mkdir mypackage
touch  mypackage/__init__.py mypackage/dummy.py

cat <<EOF > mypackage/__main__.py
from __future__ import print_function, absolute_import
import os, sys, subprocess

def rerun():
    new_environ = os.environ.copy()
    new_environ['TEST_CHILD'] = 'true'
    args = [sys.executable] + sys.argv
    subprocess.call(args, env=new_environ)

if os.environ.get('TEST_CHILD') != 'true':
    Role = 'Parent'
    rerun()
else:
    Role = 'Child'

try:
    from . import dummy
except:
    print('Exception in %s' % Role)
else:
    print('Success in %s' % Role)
EOF



Both::
	
	python2 -m mypackage

or::

	python3 -m mypackage


will print::

	Exception in Child
	Success in Parent

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#21180

On Sat, Mar 3, 2012 at 9:38 PM, Damjan Georgievski <gdamjan@gmail.com> wrote:
> How can I get the *really* original command line that started my python
> interpreter?
>
> Werkzeug has a WSGI server which reloads itself when files are changed
> on disk. It uses `args = [sys.executable] + sys.argv` to kind of
> recreate the command line, and the uses subprocess.call to run that
> command line.
>
> BUT that's problematic as, when you run::
>
>        python -m mypackage --config
>
> sys.argv printed in mypackage/__main__.py will be::
>
>        ['/full/path/to/mypackage/__main__.py', '--config']
>
> so you get::
>
>        python /full/path/to/mypackage/__main__.py --config
>
> instead of::
>
>        python -m mypackage --config
>
>
> the difference in the 2 cases is what the current package is, and
> whether you can use relative imports.

On Linux, you can read from:
    /proc/<PID here>/cmdline
to get the null-delimited "command line".

Sidenote: Consensus generally seems to be that relative imports are a bad idea.

Cheers,
Chris

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#21200

On 2012-03-04, Chris Rebert <clp2@rebertia.com> wrote:
> On Sat, Mar 3, 2012 at 9:38 PM, Damjan Georgievski <gdamjan@gmail.com> wrote:
>> How can I get the *really* original command line that started my python
>> interpreter?

> On Linux, you can read from:
>     /proc/<PID here>/cmdline
> to get the null-delimited "command line".

And if what you want is your own command line, you can replace <PID
here> with self:

/proc/self/cmdline

-- 
Grant

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#21181

On Sat, Mar 3, 2012 at 9:48 PM, Chris Rebert <clp2@rebertia.com> wrote:
> On Sat, Mar 3, 2012 at 9:38 PM, Damjan Georgievski <gdamjan@gmail.com> wrote:
>> How can I get the *really* original command line that started my python
>> interpreter?
<snip>
> On Linux, you can read from:
>    /proc/<PID here>/cmdline
> to get the null-delimited "command line".

After some further searching:
psutil offers `Process.cmdline` cross-platform;
see http://code.google.com/p/psutil/wiki/Documentation

Cheers,
Chris

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#21182

>>> How can I get the *really* original command line that started my python
>>> interpreter?
> <snip>
>> On Linux, you can read from:
>>    /proc/<PID here>/cmdline
>> to get the null-delimited "command line".
> 
> After some further searching:
> psutil offers `Process.cmdline` cross-platform;
> see http://code.google.com/p/psutil/wiki/Documentation

Indeed, changing for

	args = psutil.Process(os.getpid()).cmdline

in the above example does solve the problem, at least in Linux.


> Sidenote: Consensus generally seems to be that relative imports are a
bad idea.

How come?
I'm using explicit relative imports, I thought they were the new thing?


-- 
damjan

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#21183

On Sun, Mar 4, 2012 at 1:20 AM, Damjan Georgievski <gdamjan@gmail.com> wrote:
> How come?
> I'm using explicit relative imports, I thought they were the new thing?

Explicit relative imports are fine. Implicit relative imports can
create multiple module objects for the same source file, which breaks
things like exception handling (because exception types are unequal if
they're from different classes, even if the different classes come
from two executions of the same source code).

-- Devin

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