[Tutor] updating Unix config file

[Matt Herzog]

On Mon, Oct 19, 2009 at 07:51:06PM -0400, Matt Herzog wrote:
> On Mon, Oct 19, 2009 at 08:07:47PM +0100, Alan Gauld wrote:
> > 
> > "Matt Herzog" <msh at blisses.org> wrote
> > 
> > >remembered that strings are immutable. 
> > >So how was I able to change the strings for my dotted quad? 
> > 
> > You didn't.
> > 
> > >LASTKNOWN = '173.48.204.168'
> > >   lns = cf.readlines()
> > >   lns = "".join(lns)
> > >   lns = re.sub(LASTKNOWN, CURRENT, lns)
> > 
> > I assume this is the line in question?
> > sub() returns a new string containing the substitutions.
> > 
> > HTH,
> 
> Yes! It sure does help. I just discovered that my script does not exit if the CURRENT IP is the same as the LASTKNOWN IP. 

Please ignore the above.

> ------------------------------ snip --------------------------------------
> CURRENT = socket.getaddrinfo(socket.gethostname(), None)[0][4][0]
> ------------------------------ snip --------------------------------------
> Turns out the above is an unreliable way to get the IP of the interface since the machine the above is running on does not have a proper hostname and is a dhcp client on a broadband network. 

It's unreliable because it uses DNS, I believe. I'm not faulting the author. 

> 
> Anyway, I'd like a hint as to how I could convert this:
> 
> ifcfg_lines = os.popen("/sbin/ifconfig fxp0").readlines()
> x = string.split(ifcfg_lines[3])[1]
> 
> to the subprocess module. The os module is going away, right?
> 
> 
> > 
> > 
> > -- 
> > Alan Gauld
> > Author of the Learn to Program web site
> > http://www.alan-g.me.uk/
> > 
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> -- 
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> 
> -- F. Scott Fitzgerald
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-- 
The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function.

-- F. Scott Fitzgerald