duplicity-team team mailing list archive

[Kenneth Loafman <kenneth@xxxxxxxxxxx>]

Good catch!


On Fri, Sep 20, 2013 at 8:48 AM, edso <edgar.soldin@xxxxxx> wrote:

> On 20.09.2013 15:18, Michael Terry wrote:
> > Positive.  The first argument to exec* is the actual command to run, the
> first array item in argv is the "name" of the program passed to the command
> and is generally chopped off.
> >
> > You can test this with a simple python script:
> >
> > #!/usr/bin/python
> > import os, sys
> > print sys.argv
> > if len(sys.argv) > 1:
> >     os.execve(sys.argv[0], sys.argv[1:], os.environ)
> >
> > $ chmod +a ./test
> > $ ./test 1 2 3
> > ['./test.py', '1', '2', '3']
> > ['./test.py', '2', '3']
> > ['./test.py', '3']
> > ['./test.py']
> >
>
> weird you're right! that's strangely not explicitely documented on the
> help page. ok, now i found something close to a documentation on this.
> http://docs.python.org/2/library/os.html#process-management
> "
> The various exec*() functions take a list of arguments for the new program
> loaded into the process. In each case, the first of these arguments is
> passed to the new program as its own name rather than as an argument a user
> may have typed on a command line. For the C programmer, this is the argv[0]
> passed to a program’s main(). For example, os.execv('/bin/echo', ['foo',
> 'bar']) will only print bar on standard output; foo will seem to be ignored.
> "
>
> they'd better had documemted that they expect you to deliver a complete
> sys.argv array _incl_ the program name as argv[0]... tzzz..
>
> anyway, nice catch.. ede
>
> --
> https://code.launchpad.net/~mterry/duplicity/argv/+merge/186699
> You are subscribed to branch lp:duplicity.
>

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