strange behavior with os.system

kmw wuerzner at
Wed Jun 17 03:30:22 EDT 2009

That's it. I am calling my own program and not coreutils' sort, what
explains the unrequested output. Many thanks.


On 16 Jun., 22:16, Piet van Oostrum <p... at> wrote:
> >>>>> kmw <wuerz... at> (k) wrote:
> >k> Hi,
> >k> I wanted to write a simple script (in 5 minutes or so) which replaces
> >k> the option '+1' given to the command 'sort' by '-k 2' and than runs
> >k> 'sort' with the modified argument list. After two hours I am giving up
> >k> and ask you for help. This is what I tried (please excuse the verbose
> >k> code, it is due to my various efforts to understand the error):
> [snip]
> >k> Please note the unrequested output of '<type 'NoneType'>'. The strange
> >k> thing about this all is the fact that  the whole thing works as
> >k> expected when typed  into the interpreter. I would be glad if anyone
> >k> could help.
> MRAB has already given you some insight, I hope.
> But are you aware that you are calling your own program again?
> Or did you want to call the standard sort program? In that case you
> shouldn't call ./sort as it is in argv[0], but just sort (assuming '.'
> is not in your PATH) or the full path, like /usr/bin/sort.
> --
> Piet van Oostrum <p... at>
> URL:[PGP 8DAE142BE17999C4]
> Private email: p... at

More information about the Python-list mailing list