63

How can I get my own IP address and save it to a variable in a shell script?

  • 2
    A word of caution: There are a lot of "works on my system" answers here that may not be portable to other environments. You have to decide if you want something that works for you or something that can be shared. Every system has multiple IPs. A portable solution answers the Q: "what IP do I use to reach blah?" A works on my system solution answers the Q: "what's my IP?" with the A: "I think you mean this one…" This should be portable unix.stackexchange.com/a/402160/9745 – Bruno Bronosky Apr 1 '18 at 17:42

21 Answers 21

30

It's not so easy if you want to take into account wlan and other alternative interfaces. If you know which interface you want the address for (e.g., eth0, the first Ethernet card), you can use this:

ip="$(ifconfig | grep -A 1 'eth0' | tail -1 | cut -d ':' -f 2 | cut -d ' ' -f 1)"

In other words, get me the network configuration information, look for eth0, get that line and the next one (-A 1), get only the last line, get the second part of that line when splitting with :, then get the first part of that when splitting with space.

  • 1
    I added an additional grep to your code to ignore any interface with "eth0:" in it; this now works as I expect (giving only the "eth0" IP address and not any sub-interfaces (eth0:0, eth0:1, etc.): ip="$(ifconfig | grep -v 'eth0:' | grep -A 1 'eth0' | tail -1 | cut -d ':' -f 2 | cut -d ' ' -f 1)" – user32250 Feb 12 '13 at 19:49
  • 6
    You can skip the first grep by using ifconfig eth0 – Bryan Larsen Dec 1 '14 at 16:29
  • 4
    ifconfig is deprecated, you should use ip address instead – alexises Dec 23 '15 at 15:42
66

I believe the "modern tools" way to get your ipv4 address is to parse 'ip' rather than 'ifconfig', so it'd be something like:

ip4=$(/sbin/ip -o -4 addr list eth0 | awk '{print $4}' | cut -d/ -f1)
ip6=$(/sbin/ip -o -6 addr list eth0 | awk '{print $4}' | cut -d/ -f1)

or something like that.

  • 4
    ip is available on all the Red Hat and Fedora distros I've used. ip is part of the iproute2 package (linuxfoundation.org/collaborate/workgroups/networking/iproute2). ifconfig and route are supposedly deprecated, although they continue to be used by a lot of people, particularly in scripts. ip is much more parsable, in my opionion. – jsbillings Mar 3 '11 at 15:13
  • 3
    ip is also available on all Debian and Debian based distros I've seen. It's part of the iproute package which is marked as important. – Arrowmaster Mar 3 '11 at 23:43
  • 2
    This is absolutely how it should be done, I would downvote the other answers for their use of ifconfig. ip is part of the iproute2 package which is many a distro by default. It's in most good repos to. en.wikipedia.org/wiki/Iproute2 – jwbensley Sep 15 '12 at 12:13
  • 3
    @jsbillings Why /sbin/ip instead of ip? – l0b0 Jan 15 '13 at 13:02
  • 1
    This is an excellent answer! The combination of awk and cut is mildly amusing to me, here's a possible alternative which may not actually be better: ip -o -4 addr show eth0 | awk '{ split($4, ip_addr, "/"); print ip_addr[1] }' – Swiss Jun 15 '17 at 21:21
31

Why not simply do IP=$(hostname -I) ?

  • 3
    hostname -i gives me just 127.0.0.1, hostname -I gives me the correct IP-Adress... – student Sep 15 '12 at 12:41
  • @student yes indeed, I have tested it on a machine that has can resolve its hostname, as the manpage says -i 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 – Andrei Sep 15 '12 at 12:49
  • How can I configure my machine to resolve its hostname? – student Sep 15 '12 at 12:58
  • the easiest way is adding it to /etc/hosts, along with the corresponding IP address – Andrei Sep 16 '12 at 10:06
  • 3
    No -I on FreeBSD, but you can use dig +short `hostname -f` – Tigger Jun 3 '15 at 0:07
24

If you want the address of an interface, the easiest way is to install moreutils then:

anthony@Zia:~$ ifdata -pa br0
172.16.1.244

ifdata answers pretty much every question you'd be tempted to parse ifconfig output for.

If you want to find out your IP address as the outside sees it (beyond any NAT, etc.), there are plenty of services that'll do it. One is fairly easy:

anthony@Zia:~$ curl ifconfig.me
173.167.51.137
  • Oh goodness, thank you for this answer. Never heard of moreutils before. I was seriously considering writing my own little C program to do exactly that. – Chris Harrington Feb 28 '16 at 2:02
  • It would be nice to have ifdata added into iproute2. Maybe a new binary called ipdata – Swiss Jun 15 '17 at 21:25
  • ifdata is good BUT it doesn't supports ipv6. – BringBackCommodore64 Jul 6 '17 at 11:29
13

To get IPv4 and IPv6 addresses, and not assume the main interface is eth0 (these days em1 is more common), try:

ips=$(ip -o addr show up primary scope global |
      while read -r num dev fam addr rest; do echo ${addr%/*}; done)
  • -o uses the one-line output format, which is easier to process with read, grep, etc.
  • up excludes devices that aren't active
  • scope global excludes private/local addresses such as 127.0.0.1 and fe80::/64
  • primary excludes temporary addresses (assuming you want an address that doesn't change)
  • 1
    This has to be the best answer because 1) it doesn't assumes a device name, 2) it uses 'ip' as opposed to old school 'ifconfig', and 3) it supports ipv6 as well. – BringBackCommodore64 Jul 6 '17 at 11:31
  • I agreed, it the best start for most use cases. You can pass -4/-6 to filter address types. You can also easily get other interface parameters. Personally, I dislike while loop and I prefer grep -o 'inet6\? [0-9a-f\.:]*' | cut -f 2 -d ' ' – Jezz May 18 '18 at 7:42
7

Depends what you mean by own IP address. Systems have IP addresses on several subnets (sometimes several per subnet), some of which IPv4, some IPv6 using devices like ethernet adapters, loopback interfaces, VPN tunnels, bridges, virtual interfaces...

I you mean the IP address by which another given device may reach your computer, you have to find out which subnet that is, and which version of IP we're talking about. Also, bear in mind that because of NAT performed by firewall/routers, the IP address of an interface may not be the same as a remote host sees an incoming connection from your computer coming from.

When there is fancy source routing or per protocol/port routing it can be difficult to find out which interface would be used to talk to one remote computer over a given protocol and even then, there's no guarantee that the IP address of that interface may be directly addressable by the remote computer wanting to establish a new connection to your computer.

For IPv4 (probably works for IPv6 as well), a trick that works in many unices including Linux to find out the IP address of the interface used to reach a given host is to use a connect(2) on a UDP socket and use getsockname():

For instance, on my home computer:

perl -MSocket -le 'socket(S, PF_INET, SOCK_DGRAM, getprotobyname("udp"));
connect(S, sockaddr_in(1, inet_aton("8.8.8.8")));
print inet_ntoa((sockaddr_in(getsockname(S)))[1]);'

Would be used to find out the IP address of the interface via which I would reach 8.8.8.8 (google's DNS server). It would return something like "192.168.1.123" which is the address of the interface for the default route to the internet. However, google wouldn't see a DNS request from my machine as coming from that IP address which is a private one, as there's NAT performed by my home broadband router.

connect() on a UDP socket doesn't send any packet (UDP is connection-less), but prepares the socket by querying the routing table.

7
ipa=$(ip route get 8.8.8.8| grep src| sed 's/.*src \(.*\)$/\1/g')

ipa=$(hostname -i|cut -f2 -d ' ')
  • Using -I instead of -i is better as you would want to ignore loopback adresses, so the final command would be ipa=$(hostname -I|cut -f1 -d ' ') – Karl.S Oct 17 '17 at 22:00
  • 1
    If grep isn't enough, don't pipe it to something else. Just use the something else (sed, awk, etc.). – Bruno Bronosky Aug 11 '18 at 16:58
7

I don't mean to be a jerk, but there really is a right way and this is it. You trim the output of ip route to get only the source IP. Depending on what IP you are trying to reach, "my own ip address" (OP's words) will be different. If you care about reaching the public internet, using Google's 8.8.8.8 DNS server is pretty standard. So...

The short answer is:

ip route get 8.8.8.8 | sed -n '/src/{s/.*src *\([^ ]*\).*/\1/p;q}'

Here's the detailed explanation

If I want the ip I use to reach the internet, I use this:

pi@et3:~ $ ip route get 8.8.8.8 | sed -n '/src/{s/.*src *\([^ ]*\).*/\1/p;q}'
10.55.0.200

If I want the ip I use to reach something on my VPN, I use this:

pi@et3:~ $ ip route get 172.31.0.100 | sed -n '/src/{s/.*src *\([^ ]*\).*/\1/p;q}'
172.29.0.9

This next one is really just for illustrative purposes. But, it should work on any Linux system. So, you can use this to demonstrate that, yes, all machines have multiple IP addresses at all times.

If I wanted the ip I use to reach myself, I would use this:

pi@et3:~ $ my_ip=$(getent hosts $(cat /etc/hostname) | awk '{print $1; exit}')
pi@et3:~ $ ip route get $my_ip | sed -n '/src/{s/.*src *\([^ ]*\).*/\1/p;q}'
127.0.0.1

More about that sed command

First let me say that when choosing unix tools, you try to choose the tools that require the fewest pipes. So, while some answers will pipe ifconfig to grep to sed to head, that is rarely ever necessary. When you see it, it should raise a red flag that you are taking advice from someone with little experience. That doesn't make the "solution" wrong. But, it probably could use some streamlining.

I have chosen sed because it is more terse than the same workflow in awk. (I have since an awk example below.) I don't think any other tool but those 2 would be appropriate.

Let's examine what sed -n '/src/{s/.*src *\([^ ]*\).*/\1/p;q}' does:

sed            # the sed executable located via $PATH
-n             # no output unless explicitly requested
'              # begin the command space
/src/          # regex match the string 'src'
{              # begin a block of commands **
s/             # begin a substitution (match)
  .*src *      # match anything leading up to and including src and any number of spaces
  \([^ ]*\)    # define a group containing any number of non spaces
  .*           # match any trailing characters (which will begin with a space because of the previous rule).
/              # begin the substitution replacement
  \1           # reference the content in the first defined group
/              # end the substitution
p              # print (explicitly, remember) the result
;              # designate the end of the command
q              # quit
}              # end the block of commands
'              # end the command space

** all of which will be performed "on match"
  - otherwise only the first command to following the match would be performed "on match"
    - any other commands would be performed whether there was a match or not
Note:

I used to use sed -n '/src/{s/.*src *//p;q}' but a commenter pointed out that some systems have trailing data after the src field.

Using awk

ip route get 8.8.8.8 | \
    awk '{gsub(".*src",""); print $1; exit}'

# or

ip route get 8.8.8.8 | \
    awk '{for(i=1; i<NF; i++){if($i=="src"){i++; print $i; exit}}}'

More about my network

My ifconfig shows that I have tun0 for my VPN and eth0 for my lan.

pi@et3:~ $ ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.55.0.200  netmask 255.255.252.0  broadcast 10.55.3.255
        inet6 fe80::71e6:5d7c:5b4b:fb25  prefixlen 64  scopeid 0x20<link>
        ether b8:27:eb:b2:96:84  txqueuelen 1000  (Ethernet)

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)

tun0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 172.29.0.9  netmask 255.255.255.255  destination 172.29.0.10
        inet6 fe80::3a8e:8195:b86c:c68c  prefixlen 64  scopeid 0x20<link>
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 100  (UNSPEC)

wlan0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether b8:27:eb:e7:c3:d1  txqueuelen 1000  (Ethernet)
  • ip route get 8.8.8.8 | sed -n '/src/{s/.*src *//p;q}' gave me 10.1.2.3 uid 1002. So I add to append | awk '{print $1}' to keep only the IP address. – wisbucky Apr 23 at 21:40
  • @wisbucky I never pipe sed/awk/grep to each other in recorded code. (I will use it on the command line when I'm in a hurry, but you will never find it written to disk other than in my ~/.bash_history) I updated the answer to use awk and it solves this issue. – Bruno Bronosky Apr 24 at 15:30
  • 1
    @wisbucky I couldn't stand it. I made my sed work with your environment too. – Bruno Bronosky Apr 24 at 16:05
2

On FreeBSD you can use

dig +short `hostname -f`

This may work for other environments, depends on your set-up.

  • I believe this is dependant on the configuration of /etc/resolv.conf and how the network router handles local hostnames. It's fine to use this in your environment if you test it and it works. But if you do so, you are building a "brittle" system that is going to cause others problems if you share this. Use with caution. – Bruno Bronosky Apr 1 '18 at 17:28
2

Assuming that you may have various interfaces of various name but that you want the first non-localhost one and non-ipv6, you may try:

ip=`ip addr show |grep "inet " |grep -v 127.0.0. |head -1|cut -d" " -f6|cut -d/ -f1`
  • ip=$(ifconfig | grep -oP '(?<=inet addr:)\S*' | grep -v 127) – rcjohnson Nov 17 '15 at 17:12
1

I use this one-liner:

IP=$(/sbin/ifconfig | grep -e "inet:" -e "addr:" | grep -v "inet6" | grep -v "127.0.0.1" | head -n 1 | awk '{print $2}' | cut -c6-)

Uses ifconfig (widely available), does not take localhost address, does not bind you to a given interface name, does not take into account IPv6 and tries to get the IP of the first network interface available.

1
myip=$(curl -kLs "http://api.ipify.org")

or

myip=$(wget -q "http://api.ipify.org" -O -)
0

I needed to do this within an alias to start a radio server on my wired NIC. I used

ip addr | egrep -i "inet.+eth1" | awk -F[\ /] '{print $6}' | tr -d [:space:]
  • egrep is depreciated. Use grep -E instead. – Yokai Jan 25 '18 at 9:23
0

Some commands are working on centos 6 or 7, the below command working on both,

#!/bin/sh

serverip=`/sbin/ifconfig eth0 | grep "inet" | awk '{print $2}' | awk 'NR==1' | cut -d':' -f2`

echo $serverip
  • that's way too much grep | awk | awk . line can be shortened to /sbin/ifconfig eth0 | awk '$1 == "inet" { print substr($2,6); next ; } ' – Archemar Aug 6 '15 at 11:23
  • I accepted, can you check both centos6 and 7?. centos 7.x /sbin/ifconfig eth0 | awk '$1 == "inet" { print substr($2,6); next ; }' 35.104.41 centos6.x (Working fine) /sbin/ifconfig eth0 | awk '$1 == "inet" { print substr($2,6); next ; }' 192.168.0.1 – lakshmikandan Aug 7 '15 at 4:32
0

Assuming you need your primary public IP as it seen from the rest of the world, try any of those:

wget http://ipecho.net/plain -O - -q
curl http://icanhazip.com
curl http://ifconfig.me/ip
0

This snippet avoids hard-coding the device name (like 'eth0') and will use ip instead of ifconfig:

/sbin/ip addr | grep 'state UP' -A2 | tail -n1 | awk '{print $2}' | cut -f1  -d'/'

It will return the IP of the first active device listed in the output of ip addr. Depending on your machine, this can be an ipv4 or ipv6 address.

To store it into a variable, use:

ip=$(/sbin/ip addr | grep 'state UP' -A2 | tail -n1 | awk '{print $2}' | cut -f1  -d'/')
0

all the solutions using awk/sed/grep seem overly complex and ugly for my situation... so i came up with this really simple solution BUT beware cus it makes some assumptions, namely the assumption that the LAST interface is the one you're interested. if you're ok with that then this is pretty clean:

ifconfig | awk '/net / { x = $2 } END { print x }'

otherwise you could do some silly if statement to test for a specific prefix or whatever criteria you may have.

0

Simple Command to fine IP Address with default interface.

ip route | grep src | awk '{print $NF; exit}'

Tested on All Unix OS

0

You should use ip (instead of ifconfig) as it's current, maintained, and perhaps most importantly for scripting purposes, it produces a consistent & parsable output. Following are a few similar approaches:

If you want the IPv4 address for your Ethernet interface eth0:

$ ip -4 -o addr show eth0 | awk '{print $4}'
192.168.1.166/24  

As a script:

$ INTFC=eth0  
$ MYIPV4=$(ip -4 -o addr show $INTFC | awk '{print $4}') 
$ echo $MYIPV4
192.168.1.166/24

The output produced above is in CIDR notation. If CIDR notation isn't wanted, it can be stripped:

$ ip -4 -o addr show eth0 | awk '{print $4}' | cut -d "/" -f 1 
192.168.1.166  

Another option that IMHO is "most elegant" gets the IPv4 address for whatever interface is used to connect to the specified remote host (8.8.8.8 in this case). Courtesy of @gatoatigrado in this answer:

$ ip route get 8.8.8.8 | awk '{ print $NF; exit }'
192.168.1.166

As a script:

$ RHOST=8.8.8.8  
$ MYIP=$(ip route get $RHOST | awk '{ print $NF; exit }')
$ echo $MYIP
192.168.1.166

This works perfectly well on a host with a single interface, but more advantageously will also work on hosts with multiple interfaces and/or route specifications.

ip would be my preferred approach, but it's certainly not the only way to skin this cat. Here's another approach that uses hostname if you prefer something easier/more concise:

$ hostname --all-ip-addresses | awk '{print $1}'  

Or, if you want the IPv6 address:

$ hostname --all-ip-addresses | awk '{print $2}'  
0

This may not be the most robust or correct solution, but unlike most of the other solutions, the command works on both Linux and Mac (BSD).

host `hostname` | awk '{print $NF}'
-2
hostname -I >> file_name 

this will do everything you want

  • hostname: invalid option -- 'l'... – jasonwryan Dec 23 '15 at 6:56
  • That's a capital i. Seems to work fine although it apparently prints IP addresses of all interfaces. – Joe Dec 23 '15 at 7:04
  • it is proposed in one of the previous answers. Also it does not store the IP in the variable. So what is the point of this answer? – Jakuje Dec 23 '15 at 8:10

protected by jasonwryan Dec 23 '15 at 6:59

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.