Linux: How to get a machine's IP address?

Question

I'm using Linux CentOS 6.4 .

I'm writing a shell script and I need to extract a machine's IP in order to use it in the script. How can I find the machine's IP?

I'm looking for the "best" way because I know there are a few ways to get IP addresses.

Thanks

score 7 · Accepted Answer · answered Feb 09 '15 at 14:30

7

Here are ways to get your Linux machine IP address:

/sbin/ifconfig

If you know the name of your Network Interface card, you can specify it in the command and get the results for that specific NIC:

/sbin/ifconfig eth0

Another command is:

/sbin/ip addr

If you know the name of your Network Interface card, you can specify it in the command and get the results for that specific NIC:

/sbin/ip addr show eth0

I think this is the best way:

hostname -i

Bare in mind that in some servers you might have more than one Network Interfacr Cards...

answered Feb 09 '15 at 14:30

Itai Ganot

That was quick! thank you! I think I'll use the `hostname -i` one. – Feb 09 '15 at 14:31
use of hostname -i is discouraged in the manpage: Display the network address(es) of the host name. Note that this works only if the host name can be resolved. Avoid using this option; use hostname --all-ip-addresses instead. – andrekeller Feb 09 '15 at 14:34
In case your machine is behind a router and you need your public IP you can use this service: `curl ifconfig.me` – r_3 Feb 09 '15 at 16:07

score 0 · Answer 2 · answered Feb 09 '15 at 14:32

0

I'd use facter for that.

yum install facter
facter ipaddress
facter ipaddress_eth0

answered Feb 09 '15 at 14:32

andrekeller

Isn't facter related to Puppet or something like that? – Feb 09 '15 at 14:32
yes it comes from the puppet ecosystem, but works perfectly fine as standalone application. – andrekeller Feb 09 '15 at 14:34
Facter is related to Puppet, yes, but you can use Facter without Puppet (though not the other way around). – Craig Watson Feb 09 '15 at 14:34

2 Answers2