[RndTbl] determine IP address in linux

Sean Walberg sean at ertw.com
Sat Mar 23 22:45:31 CDT 2013

my_public_ip=`curl http://ifconfig.me`

On Sat, Mar 23, 2013 at 10:40 PM, Trevor Cordes <trevor at tecnopolis.ca>wrote:

> Seems simple.  What's the best way (in a script) to get the IP address of
> an ethernet interface (in linux).  For instance eth0.
> I used to have (perl, but also applies as a bash solution):
> $eip=`/sbin/ifconfig $int | grep 'inet addr' | awk '{print \$2}' | sed -e
> 's/.*://'`
> But the latest upgrade from F16 to F17 broke this (now the line contains
> "inet" but not "inet addr".
> So I started thinking of finding the most standardized way that
> (hopefully) won't change after a future kernel upgrade :-)
> It would seem that the less field parsing done, the better, as keywords
> and field position aren't guaranteed.
> Looks like ifconfig is now deprecated (according to man ifconfig).  So now
> I'm doing:
> $eip=`ip -o -4 addr list eth0 | awk '{print \$4}'`
> That works now, but it still has a output format-dependent requirements.
> I looked for /sys or /dev files, but can't find any that have ip4 addr.  I
> tried to find more options to whittle ip's output to give me just the
> address, no joy there.
> Ideas?
> PS: this is important as failures like this force me to drive out onsite
> to headless boxes, some of which are 200km away.
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Sean Walberg <sean at ertw.com>    http://ertw.com/
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