netdev - Re: Find IP address of active interface

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Date:   Mon, 25 Jul 2022 11:07:42 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     "Kai Hendry" <hendry@....fi>
Cc:     netdev@...r.kernel.org
Subject: Re: Find IP address of active interface

On Mon, 25 Jul 2022 08:48:15 +0800
"Kai Hendry" <hendry@....fi> wrote:

> Is there an easier way than:
> 
> ip route get 8.8.8.8 2>/dev/null|grep -Eo 'src [0-9.]+'|grep -Eo '[0-9.]+'
> 
> To figure out the active, Internet routing interface?
> 
> Thank you,

Alternate:

$ ip -j route get 8.8.8.8 | \
  python3 -c 'import json,sys;obj=json.load(sys.stdin);print(obj[0]["dev"]);'
enp2s0

But both options won't do what you want if there is ECMP routes.