From ripley at stats.ox.ac.uk  Fri Jun 22 13:40:38 2007
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Fri, 22 Jun 2007 12:40:38 +0100 (BST)
Subject: [Rd] Cross-platform check for internet connection
In-Reply-To: <f8e6ff050706220114gb008b92ib58e151e4742f774@mail.gmail.com>
References: <f8e6ff050706220114gb008b92ib58e151e4742f774@mail.gmail.com>
Message-ID: <Pine.LNX.4.64.0706221117520.21000@gannet.stats.ox.ac.uk>

On Fri, 22 Jun 2007, hadley wickham wrote:

> What's the recommended way to check if an internet connection is
> available across platforms?  I was using is.null(nsl()) but this does
> not work on windows.

I don't know a way to do this on Windows without a possible very long 
hang.  It's complicated by the use of two alternative internet connection 
mechanisms on Windows and having little control over the IE-based one.

Another issue is software firewalls: they can take many minutes to 
decide to let a new program talk to the Internet if they 'call home' to 
ask advice.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595



[Rd] Cross-platform check for internet connection
Prof Brian Ripley