Retrieving the full command line

Oscar Benjamin oscar.j.benjamin at gmail.com
Thu Jan 24 17:08:50 CET 2013


On 24 January 2013 15:51, Tim Golden <mail at timgolden.me.uk> wrote:
> On 24/01/2013 15:28, Oscar Benjamin wrote:
>> On 24 January 2013 13:45, Tim Golden <mail at timgolden.me.uk> wrote:
>>> On 24/01/2013 11:30, Oscar Benjamin wrote:
>>>> I don't really understand what your spec is. Why do you need to
>>>> inspect this information from sys.argv? Can you not just always use
>>>> 'python -m pkg' as your entry point?
>>>
>> [SNIP]
>>>
>>> For completeness, I'm talking about the cherrypy Autoreloader which
>>> attempts to restart (via execv) whatever process was responsible for
>>> loading it in the first place, via an identical or equivalent command
>>> line. The current (cherrypy) code simply joins sys.executable and
>>> sys.argv but this fails in the face of python -m as we have seen.
>>>
>>> The cherrypy package has no especial knowledge of the structure of the
>>> application which imported it and so must piece together the command
>>> line somehow. Clearly, I can take various approaches of the sort
>>> which you've outlined, or subclass the reloader, or fetch the original
>>> command line from the OS, etc. It's not that this is a showstopper,
>>> merely slightly surprising. (To me).
>>
>> Ok I understand. Then I guess you want:
>>
>> import __main__
>> pkg = __main__.__package__
>
> Brilliant. Never thought of importing __main__. Thanks.
>
> For the benefit of anyone still watching, the code (which has to be
> compatible back to 2.3) looks something like this:
>
> <code>
> import __main__
>
> # [.. .snip ...]
>
> try:
>     is_package = bool(__main__.__package__)
> except NameError:
>     is_package = False
> if is_package:
>     args = [sys.executable, '-m', __main__.__package__] + sys.argv[1:]
> else:
>     args = [sys.executable] + sys.argv
>
> os.chdir(_startup_cwd) # avoids relative/absolute issues
> os.execv(args[0], args)
>
> </code>
>
> I don't pretend it's foolproot, but it certainly works for my particular
> case. Nor have I considered it against all the cases identified in PEP
> 432: http://www.python.org/dev/peps/pep-0432/#configuring-sys-argv

Does it work if you use the -m option to run a module rather than a script?


Oscar



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