Which terminal command to get just IP address and nothing else?

Question

I\'m trying to use just the IP address (inet) as a parameter in a script I wrote.

Is there an easy way in a unix terminal to get just the IP address, rather than loo

Answer 1

Generally, it is never guaranteed that a system will only have one IP address, for example, you can have both an ethernet and wlan connections, and if you have an active VPN connection then you'll have yet another IP address.

Linux

On Linux, hostname -I will list the current IP address(es). Relying on it always returning just one IP address will most likely not work as expected under some scenarios (i.e. a VPN link is up), so a more reliable way would be converting the result to an array and then loop over the elements:

ips=($(hostname -I))

for ip in "${ips[@]}"
do
    echo $ip
done

OSX

On OSX, if you know the interface, you could use:

~$ ipconfig getifaddr en0
192.168.1.123

which will return just the IP address.

Or you could loop over possible interface names, starting with a suffix, i.e. en:

for NUMBER in $(seq 0 5); do
    ip=`ipconfig getifaddr en$NUMBER`
    if [ -n "$ip" ]; then
        myip="$ip"
        break
    fi
done

echo $myip

Also, getting the IP address becomes non-deterministic in case both a cable and wifi connections are established, when a machine has more than one ethernet interfaces, or when VPN tunnels are present.

Getting the external IP

If you need the external IP, then you can query a text-mode service, for example curl https://ipecho.net/plain would return a plain text external IP.

And an even faster way to get the external IP is to query a known DNS server:

dig @ns1-1.akamaitech.net ANY whoami.akamai.net +short

Answer 2

I don't see any answer with nmcli yet which is a command-line tool for controlling NetworkManager.

So here you go :)

wolf@linux:~$ nmcli device 
DEVICE  TYPE      STATE        CONNECTION 
eth1    ethernet  unavailable  --         
eth0    ethernet  unmanaged    --         
lo      loopback  unmanaged    --         
wolf@linux:~$ 

If you want to get the information from specific network interface (let say lo for this example)

wolf@linux:~$ nmcli device show lo
GENERAL.DEVICE:                         lo
GENERAL.TYPE:                           loopback
GENERAL.HWADDR:                         00:00:00:00:00:00
GENERAL.MTU:                            65536
GENERAL.STATE:                          10 (unmanaged)
GENERAL.CONNECTION:                     --
GENERAL.CON-PATH:                       --
IP4.ADDRESS[1]:                         127.0.0.1/8
IP4.GATEWAY:                            --
IP4.ROUTE[1]:                           dst = 127.0.0.0/8, nh = 0.0.0.0,>
IP4.ROUTE[2]:                           dst = 127.0.0.1/32, nh = 0.0.0.0>
IP6.ADDRESS[1]:                         ::1/128
IP6.GATEWAY:                            --
IP6.ROUTE[1]:                           dst = ::1/128, nh = ::, mt = 256
IP6.ROUTE[2]:                           dst = ::1/128, nh = ::, mt = 0, >
wolf@linux:~$ 

But since you just want to get the IP address, just send the output to grep, cut or awk.

Let's do it step by step. (Not sure what's wrong, the code sample format just didn't work for these 3 example.)

1. Get the IPv4 line

   wolf@linux:~$ nmcli device show lo | grep 4.A IP4.ADDRESS[1]: 127.0.0.1/8 wolf@linux:~$

2. Use awk to get the IP

   wolf@linux:~$ nmcli device show lo | awk '/4.A/ {print $2}' 127.0.0.1/8 wolf@linux:~$

3. Use cut to remove the CIDR notation (/8)

   wolf@linux:~$ nmcli device show lo | awk '/4.A/ {print $2}' | cut -d / -f1 127.0.0.1 wolf@linux:~$

There your answer.

Please take note that there are tons of ways to do it using the tools that I demonstrated just now.

Let's recap the commands that I used.

nmcli device show lo | grep 4.A
nmcli device show lo | awk '/4.A/ {print $2}'
nmcli device show lo | awk '/4.A/ {print $2}' | cut -d / -f1

Sample output for these 3 commands

Command 1 output

IP4.ADDRESS[1]:                         127.0.0.1/8

Command 2 output

127.0.0.1/8

Command 3 output

127.0.0.1

Answer 3

These two ways worked for me:

To get IP address of your interface eth0. Replace eth0 in the below example with your interface name. ifconfig eth0 | grep -w "inet" | tr -s " " | cut -f3 -d" "

Using hostname: This will give you the inet i.e. IPAddress of your etho. using -I will give you inet value of all the interfaces whereever this value is present.

hostname -i

Answer 4

When looking up your external IP address on a NATed host, quite a few answers suggest using HTTP based methods like ifconfig.me eg:

$ curl ifconfig.me/ip

Over the years I have seen many of these sites come and go, I find this DNS based method more robust:

$ dig +short myip.opendns.com @resolver1.opendns.com

I have this handy alias in my ~/.bashrc:

alias wip='dig +short myip.opendns.com @resolver1.opendns.com'

Answer 5

To get only the IP address on Mac OS X you can type the following command:

ipconfig getifaddr en0

Answer 6

I prefer not to use awk and such in scripts.. ip has the option to output in JSON.

If you leave out $interface then you get all of the ip addresses:

ip -json addr show $interface | \
  jq -r '.[] | .addr_info[] | select(.family == "inet") | .local'