Run pyc file without specifying python path ?

Dave Angel davea at dejaviewphoto.com
Thu Jul 30 19:07:43 CEST 2009


Barak, Ron wrote:
> Hi Dave,
>
> On second thoughts, I may have a problem implementing the wrapper solution, because my actual test_pyc.pyc, needs to parse its command line.
> Namely, the actual call to test_pyc.pyc looks something like this:
>
> $ python  test_pyc.py -U dave -PpasswoRD -C CreateMcGroupOnVolume --SVMs_IPs '10.1.1.1 , 10.1.1.2' -n "host1,host2" -g gn -j jn -s svn -t tvn -p pool1 -l -c
>
> And I don't know of a way to add these parameters to the "import  test_pyc" in wrapper
>
> Is there a way to pass information to an imported module ? (Sorry if there's an obvious answer, I just cannot figure it out).
>
> Bye,
> Ron.
>
>   
>> -----Original Message-----
>> From: Dave Angel [mailto:davea at dejaviewphoto.com] 
>> Sent: Thursday, July 30, 2009 16:03
>> To: Barak, Ron
>> Cc: 'Dave Angel'; 'python-list at python.org'
>> Subject: RE: Run pyc file without specifying python path ?
>>
>> Barak, Ron wrote:
>>     
>>>> -----Original Message-----
>>>> From: Dave Angel [mailto:davea at ieee.org]
>>>> Sent: Wednesday, July 29, 2009 21:05
>>>> To: Barak, Ron
>>>> Cc: 'python-list at python.org'
>>>> Subject: Re: Run pyc file without specifying python path ?
>>>>
>>>> Barak, Ron wrote:
>>>>     
>>>>         
>>>>> Hi,
>>>>>
>>>>> I wanted to make a python byte-code file executable,
>>>>>       
>>>>>           
>>>> expecting to be able to run it without specifying "python" on the 
>>>> (Linux bash) command line.
>>>>     
>>>>         
>>>>> So, I wrote the following:
>>>>>
>>>>> [root at VMLinux1 python]# cat test_pyc.py #!/usr/bin/env python
>>>>>
>>>>> print "hello"
>>>>> [root at VMLinux1 python]#
>>>>>
>>>>> and made its pyc file executable:
>>>>>
>>>>> [root at VMLinux1 python]# ls -ls test_pyc.pyc
>>>>> 4 -rwxr-xr-x  1 root root 106 Jul 29 14:22 test_pyc.pyc
>>>>> [root at VMLinux1 python]#
>>>>>
>>>>> So, I see:
>>>>>
>>>>> [root at VMLinux1 python]# file test_pyc.py*
>>>>> test_pyc.py:  a python script text executable
>>>>> test_pyc.pyc: python 2.3 byte-compiled
>>>>> [root at VMLinux1 python]#
>>>>>
>>>>> If I try to do the following, no problem:
>>>>>
>>>>> [root at VMLinux1 python]# python test_pyc.pyc hello
>>>>> [root at VMLinux1 python]#
>>>>>
>>>>> However, the following fails:
>>>>>
>>>>> [root at VMLinux1 python]# ./test_pyc.pyc
>>>>> -bash: ./test_pyc.pyc: cannot execute binary file
>>>>> [root at VMLinux1 python]#
>>>>>
>>>>> Is there a way to run a pyc file without specifying the
>>>>>       
>>>>>           
>>>> python path ?
>>>>     
>>>>         
>>>>> Bye,
>>>>> Ron.
>>>>>
>>>>>   
>>>>>       
>>>>>           
>>>> I don't currently run Unix, but I think I know the problem.
>>>>
>>>> In a text file, the shell examines the first line, and if 
>>>>         
>> it begins 
>>     
>>>> #!
>>>> it's assumed to point to the executable of an interpreter for that 
>>>> text file.  Presumably the same trick doesn't work for a .pyc file.
>>>>
>>>> Why not write a trivial wrapper.py file, don't compile it, and let 
>>>> that invoke the main code in the .pyc file?
>>>>
>>>> Then make wrapper.py executable, and you're ready to go.
>>>>
>>>> DaveA
>>>>
>>>>
>>>>     
>>>>         
>>> Hi Dave,
>>> Your solution sort of defeats my intended purpose (sorry 
>>>       
>> for not divulging my 'hidden agenda').
>>     
>>> I wanted my application to "hide" the fact that it's a 
>>>       
>> python script, and look as much as possible like it's a 
>> compiled program.
>>     
>>> The reason I don't just give my user a py file, is that I 
>>>       
>> don't want a cleaver user to change the innards of the script.
>>     
>>> On the other hand, I don't want to make a compiled 
>>>       
>> (freezed?) version of the application, because it'll grow the 
>> resulting file significantly, and I don't have the experience 
>> to know how it will run on different Linuxes.
>>     
>>> Bye,
>>> Ron. 
>>>   
>>>       
>> Most of the other answers basically paraphrased my suggestion 
>> of making a wrapper file, not compiling it, and making it 
>> executable.  With that 
>> approach, the user just types   "wrapper.py" on his command line.
>>
>> And wrapper.py only needs two lines, a shebang, and an 
>> import, no big deal if the user modifies it.  The rest of 
>> your code can be .pyc files.
>>
>> Steven makes some good points.  You have to define what level 
>> of clever you're protecting from.  A determined hacker will 
>> get in no matter what you do, unless you want to ship the 
>> program in a proprietary embedded system, encased in epoxy.  
>> Further, if you have an extension of .py or .pyc, a 
>> knowledgeable hacker will know it's probably python.
>>
>> You imply you want it to run unmodifed on multiple unknown 
>> Linux versions.  I think that lets out binfmt solutions.  
>> That means you need to test and support not only multiple 
>> Linux implementations, but multiple Python versions, because 
>> who knows what the user may have installed.  I think you need 
>> to rethink your support strategy.  And maybe concentrate on 
>> being able to detect change, rather than prevent it.
>>
>> DaveA
>>
>>
>>
>>     
(Please don't top-post.  It puts responses out of order)

You don't have to do anything special.  Any module can import sys, and 
parse sys.argv, as long as it wasn't yet modified.

DaveA



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