Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!feeder.news-service.com!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Date: Fri, 10 Jun 2011 18:41:12 +0100
From: MRAB <python@mrabarnett.plus.com>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10
MIME-Version: 1.0
To: python-list@python.org
Subject: Re: Question About Command line arguments
References: <BANLkTi==QHd+5C=xf+2Re1Mh4V6Hk972hg@mail.gmail.com>
In-Reply-To: <BANLkTi==QHd+5C=xf+2Re1Mh4V6Hk972hg@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: list
Reply-To: python-list@python.org
Newsgroups: comp.lang.python
Message-ID: <mailman.89.1307727680.11593.python-list@python.org>
Lines: 28
NNTP-Posting-Host: 82.94.164.166
Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:7389

On 10/06/2011 18:21, Mark Phillips wrote:
> I have a script that processes command line arguments
>
> def main(argv=None):
>      syslog.syslog("Sparkler stared processing")
>      if argv is None:
>          argv = sys.argv
>      if len(argv) != 2:
>          syslog.syslog(usage())
>      else:
>          r = parseMsg(sys.argv[1])
>          syslog.syslog(r)
>      return 0
>
> if __name__ == "__main__":
>      sys.exit(main())
>
> When I run "python myscript fred" it works as expected - the argument
> fred is processed in parseMsg as sys.arv[1]
>
> When I run "echo fred | python myscript" the script thinks there are no
> arguments, so it prints out the usage statement.
>
> Is the problem with the echo command, or how I wrote my script?
>
In the second case, there aren't any arguments. The echo command is
writing "fred" to its standard output, which is attached to your
script's standard input.