[Tutor] missing first argument on subprocess.Popen w/ executable

[Lie Ryan]

A.T.Hofkamp wrote:
> Lie Ryan wrote:
>> I'm wondering whether I have misunderstood the documentation or this is
>> a bug in either the documentation or the python:
>>
>> Python 2.5.4 (r254:67916, May 18 2009, 20:53:31)
>> [GCC 4.3.2] on linux2
>> Type "help", "copyright", "credits" or "license" for more information.
>>>>> import subprocess
>>>>> subprocess.Popen(['a', 'b', 'c', 'd'], executable='echo')
>> <subprocess.Popen object at 0x7fdf7bb2bd50>
>> b c d
>>
>> shouldn't the output be
>> a b c d
>>
>> where has the first argument (a) gone to?
> 
> Under Unix, it is the displayed executable name eg in 'ps':
> 
>>>> import subprocess
>>>> subprocess.Popen(['60', '60'], executable='/bin/sleep')
> <subprocess.Popen object at 0xb7ee0e6c>
> 
> 
> While it is running, 'ps' lists
> 
> USER       PID %CPU %MEM  VSZ  RSS TTY      STAT START   TIME COMMAND
> user     26056  0.1  0.0  8140 3480 pts/11   S+   11:13   0:00 python
> user     26059  0.0  0.0  5796  560 pts/11   S+   11:14   0:00 60 60

Now THAT is bizarre. Any word on Windows?

>> Normally the first argument in arg is the executable name, however we
>> may also specify it as executable argument instead; but what's the
>> rationale for zapping the first argument when executable is present?
> 
> It is still the name of the executable, the value is just not used for
> searching the program, rather just displayed.
> 
>> Or is it because I'm using a (rather) old version of python (the default
>> python from Gentoo amd64)
> 
> Nope, it is feature of the OS. No way around it unless you patch the
> kernel.

If it's indeed a feature, shouldn't it be mentioned in the documentation
(or at least a warning for unsuspecting user)? Or even better, shouldn't
a separate argument (e.g. displayed_executable_name) be used? Either
way, I'll try to put this to the bug tracker...