Re: what's the right way to resolve localhost's IPs

[Gregory Seidman <gsslist+debian@anthropohedron.net>]

On Wed, Mar 22, 2023 at 10:06:40AM +0800, Jeremy Ardley wrote:
> 
> On 22/3/23 09:12, fh@dnsbed.com wrote:
> > Hello,
> > 
> > In my shell script, how to get the localhost's IPs (eth0 and eth1)
> > correctly?
> > I know I can run 'ifconfig' and grep etc, but it's maybe not that
> > graceful.
> 
> On Debian the preferred  command is
> 
> root@debian12:~# ip a
[...]
> You can also output in .json format
> 
> root@debian12:~# ip -j a
[...]
> 
> and if you write a script like this (and make it write protected and
> executable)
[...]

For those of us who like using jq for this kind of thing:

#!/bin/sh

ip -j a | jq -r '
	.[] | {
		"name": .ifname,
		"addr": .addr_info |
			map(select(.family ==  "inet")) |
			.[0].local
	} |
	select(.addr) |
	.name + ": " + .addr'

> you can do
> 
> ip -j a | ./ipv4_addresses.py
> lo: 127.0.0.1
> enp7s0: 10.31.40.68
> 
> or on a fancier setup
> 
> ip -j a | ./ipv4_addresses.py
> lo: 127.0.0.1
> eth0: 10.31.40.4
> eth0: 10.31.40.5
> eth0: 10.31.40.101
> docker0: 172.17.0.1
> 
> > -- 
> 
> Jeremy
> (Lists)
--Gregory