Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!1.eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed3a.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.008 X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; 'python,': 0.02; 'exit': 0.07; 'get.': 0.09; 'integers': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'returns,': 0.09; 'statements': 0.09; 'programs.': 0.11; 'subject:error': 0.11; 'literals,': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'status.': 0.16; 'comparing': 0.18; 'integer': 0.18; 'recognize': 0.22; 'code.': 0.23; 'sets': 0.23; 'header:User-Agent:1': 0.26; 'header:X-Complaints-To:1': 0.26; 'external': 0.27; 'error': 0.27; "skip:' 10": 0.30; 'values': 0.30; 'source': 0.31; 'gets': 0.32; 'to:addr:python-list': 0.35; 'but': 0.36; 'except': 0.36; 'there': 0.36; 'child': 0.36; 'subject:: ': 0.37; 'received:org': 0.38; 'say': 0.38; 'is,': 0.38; 'means': 0.39; 'whatever': 0.39; 'to:addr:python.org': 0.39; 'where': 0.40; 'some': 0.40; 'further': 0.60; "you'll": 0.61; 'different': 0.64; 'between': 0.65; '8bit%:40': 0.66; 'born': 0.66; 'skip:\xe2 10': 0.70; '8bit%:20': 0.72; '_o__)': 0.84; 'received:125': 0.84; 'vatican': 0.84; 'mean.': 0.91; '\xe2\x80\x9cthe': 0.93 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Ben Finney Subject: Re: os.system error returns Date: Fri, 12 Jun 2015 23:43:04 +1000 References: <2ebdfdf225c075b2f5ef350b06bc14f0@myglnc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Gmane-NNTP-Posting-Host: jigong.madmonks.org X-Public-Key-ID: 0xAC128405 X-Public-Key-Fingerprint: 517C F14B B2F3 98B0 CB35 4855 B8B2 4C06 AC12 8405 X-Public-Key-URL: http://www.benfinney.id.au/contact/bfinney-pubkey.asc X-Post-From: Ben Finney User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) Cancel-Lock: sha1:uuti8IXk7R5/SDSIY4+V8//GuTY= X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.20+ Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 34 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1434116599 news.xs4all.nl 2934 [2001:888:2000:d::a6]:50114 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:92520 Grawburg writes: > if os.system('modprobe --first-time -q w1_gpio') ==0 > > if os.system('modprobe -q w1_gpio') == 256: > > I know what the 'modprobe...' is, it's the 0 and the 256 I don't get. > Where do these numbers come from? They are integer literals, they come from the source code. The statements are comparing those integers to the return value from ‘os.system’. The return value from ‘os.system’ is whatever was the child process sets as its exit status. > I recognize they're some kind of error returns, but don't know what > they mean. That's not up to Python, it's entirely set by the external program. There is no standardisation of exit status values between different programs. The best one can say is “exit status 0 means success”. Anything further is specific to particular programs and is not universal. You'll need to see the documentation for ‘modprobe(1)’ to find out what its different exit status values mean. -- \ “The Vatican is not a state.… a state must have people. There | `\ are no Vaticanians.… No-one gets born in the Vatican except by | _o__) an unfortunate accident.” —Geoffrey Robertson, 2010-09-18 | Ben Finney