[Baypiggies] Locating the directory you are executing from

[Kelly Yancey]

Shannon -jj Behrens wrote:
> Furthermore, if you run your script like "$ script.py", and it runs
> because "." is in $PATH, I'm guessing that argv[0] won't have the full
> path, but __file__ will.  (By the way, "." is not in my path.)
> 
> -jj
> 

   Maybe on linux and un*x-like systems.

   Unfortunately, on Windows this is not the case: argv[0] == __file__ 
for the main script *unless* you compile your script into an executable 
using py2exe...in which case __file__ is not defined for the main script.

 > type test.py
import sys
import os

print "sys.executable :", os.path.dirname(sys.executable)
print "sys.argv[0]    :", os.path.dirname(sys.argv[0])
print "__file__       :", os.path.dirname(__file__)

 > python test.py
sys.executable : c:\python25
sys.argv[0]    :
__file__       :

 > python "c:\Documents and Settings\Kelly"\test.py"
sys.executable : c:\python25
sys.argv[0]    : c:\Documents and Settings\Kelly
__file__       : c:\Documents and Settings\Kelly


   Using py2exe to build a standalone executable...

 > type setup.py
from distutils.core import setup
import py2exe

setup(console=['test.py'])

 > test.exe
sys.executable : c:\Documents and Settings\Kelly\dist
sys.argv[0]    :
__file__       :
Traceback (most recent call last):
   File "test.py", line 5, in ?
NameError: name '__file__' is not defined

 > "c:\Documents and Settings\Kelly\dist\test.exe"
sys.executable : c:\Documents and Settings\Kelly\dist
sys.argv[0]    : c:\Documents and Settings\Kelly\dist
__file__       :
Traceback (most recent call last):
   File "test.py", line 5, in ?
NameError: name '__file__' is not defined

   For Windows, sys.argv[0] would appear to be the best bet.  If this is 
different on un*x-like systems, though, then people just need to beware 
when trying to write portable code.

   Kelly

> On Tue, May 6, 2008 at 11:04 PM, Atul Varma <varmaa at gmail.com> wrote:
>> I think one nice thing about using __file__ is that it doesn't necessarily
>> require your Python file to be the main script that's being executed, as
>> sys.argv[0] does.  For instance, I could have my own script called "foo",
>> and then import "bar", which loads something relative to its (i.e., bar's)
>> location in the filesystem.  If "bar" uses sys.argv[0], it would find the
>> path to foo, but if it uses __file__, it will always find the correct path
>> regardless of whether it's imported as a module or run as a script.
>>
>> - Atul
>>
>>
>>
>> On Tue, May 6, 2008 at 10:22 PM, Kelly Yancey <kelly at nttmcl.com> wrote:
>>>
>>>
>>>
>>> Shannon -jj Behrens wrote:
>>>
>>>> On Sun, May 4, 2008 at 1:15 PM, Aahz <aahz at pythoncraft.com> wrote:
>>>>
>>>>> On Sun, May 04, 2008, Jeff Younker wrote:
>>>>>  >
>>>>>  > I have a set of development scripts.  The scripts can potentially
>>>>>  > be executed from many places.  They reference information which is
>>>>>  > relative to their installation paths.  (These are build scripts.)
>>>>>  >
>>>>>  > The CI system can supply a fixed root, but when run by the
>> developers
>>>>>  > I'd like them to be runnable from anywhere in the project, and
>> still
>>>>>  > have them work.
>>>>>
>>>>>  If you're willing to require that the script directory NOT be on the
>>>>>  path, just do some manipulation of sys.argv[0].  Otherwise, __file__
>> is
>>>>>  the right approach.
>>>>>
>>>> Heh, I have this same problem ;)
>>>>
>>>> -jj
>>>>
>>>>
>>>  Here is the snippet I've been using.  It supports running both as a
>> python script and as a binary created by py2exe.  It also works on systems
>> that return paths encoded with with non-ASCII character sets (e.g. non-U.S.
>> version of Windows).
>>>    import locale
>>>    import os
>>>    import sys
>>>
>>>    if hasattr(sys, 'frozen'):
>>>        # Running as executable generated by py2exe.
>>>        runpath = sys.executable
>>>    else:
>>>        # Running as python script.
>>>        runpath = sys.argv[0]
>>>    rundir = os.path.dirname(unicode(runpath,
>>>                                     locale.getpreferredencoding()))
>>>
>>>  I am curious though: how is extracting the path from __file__ better than
>> extracting it from sys.argv[0]?  The best I can tell (from simple test
>> scripts) is that both yield the same results.
>>>  Kelly
>>>
>>> --
>>> Kelly Yancey
>>> http://kbyanc.blogspot.com/
>>>
>>>
>>>
>>>
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>>
> 
> 
>