Q. I need to get the IP address assigned to eth0 Linux interface. How do I find out IP address only? I don't want other information displayed by Linux ifconfig command.
A. For shell script or may be for other cause you may need the IP address only. You can use ifconfig command with grep and other filters.
Default output of /sbin/ifconfig command is all interfaces:
$ /sbin/ifconfigOutput:
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:69527 errors:0 dropped:0 overruns:0 frame:0
TX packets:69527 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:41559546 (39.6 MiB) TX bytes:41559546 (39.6 MiB)
eth0 Link encap:Ethernet HWaddr 00:17:9A:0A:F6:44
inet addr:192.168.2.1 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::217:9aff:fe0a:f644/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:227614 errors:0 dropped:0 overruns:0 frame:0
TX packets:60421 errors:0 dropped:0 overruns:0 carrier:0
collisions:272 txqueuelen:1000
RX bytes:69661583 (66.4 MiB) TX bytes:10361043 (9.8 MiB)
Interrupt:17
ra0 Link encap:Ethernet HWaddr 00:50:56:C0:00:01
inet addr:192.168.1.2 Bcast:192.168.2.255 Mask:255.255.255.0
inet6 addr: fe80::250:56ff:fec0:1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1024 errors:0 dropped:0 overruns:0 frame:0
TX packets:1320 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)Now you just select eth0 as follows:
$ /sbin/ifconfig eth0
Now you just wanted the IP address, use grep to get the IP:
$ /sbin/ifconfig eth0| grep 'inet addr:'Output:
inet addr:192.168.2.1 Bcast:192.168.2.255 Mask:255.255.255.0
To get IP address from use cut command:
$ /sbin/ifconfig eth0 | grep 'inet addr:' | cut -d: -f2Output:
192.168.2.1 Bcast
Finally remove Bcast with awk
$ /sbin/ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}'
Output:
192.168.2.1
See how to read UNIX/Linux system IP address in a shell script
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{ 20 comments… read them below or add one }
if u have idea to configar different server on linux and network plsase send me all informatios ….
with thanks
another option is to use “ip” command:
ip addr list eth0 |grep inet |cut -d' ' -f6|cut -d/ -f1which prints both ipv4 and ipv6 addresses, ipv4 addr can be printed using tighter grep expression:
IPv4:
ip addr list eth0 |grep "inet " |cut -d' ' -f6|cut -d/ -f1IPv6:
ip addr list eth0 |grep "inet6 " |cut -d' ' -f6|cut -d/ -f1For those on OS X’s Terminal.app:
ifconfig en1 | grep 'inet ' | cut -d ' ' -f 2thank you, exactly what I’m looking for (now in my bash profile):
alias ip=”ifconfig en0 | grep ‘inet ‘ | cut -d ‘ ‘ -f 2″
for OS X this is much better.
ipconfig getifaddr en0
ipconfig getifaddr en1
ifconfig eth0 | sed -n ‘s/.*dr:\(.*\) Bc.*/\1/p’
$ hostname -i
Bash-script: http://users.telenet.be/x86_64/Scripts/IP.check
Put it in your “.bashrc” file.
Output when you start a konsole/terminal:
WAN IP: xxx.yyy.zzz.aaa
LAN IP: bbb.ccc.ddd.eee
Bob wins. The rest of you should go self-flagellate for being moronic punks.
Rules of thumb for efficient text processing:
a. Avoid the need to do so. If there’s a command that outputs exactly what you need, use it. (For example, in our case here, using ‘hostname -i’ instead of stupidly dicking around with ifconfig, cut, grep, sed, and awk). Use some common sense, for Christ’s sake. Think maybe nobody else ever needed to include their IP address in a command? Before you go monkey-spanking around with awk or perl, see if there’s an appropriate command.
b. if there’s a shell built-in that can do it, use that (your shell is already loaded into memory, and there is overhead in making a call to an external). For example, if you can parse a line effectively using the shell’s string substitution features, then do so. Don’t be a dumb-ass and waste your RAM and CPU. Read your shell’s man page.
b. If the shell can’t do it, use the simplest alternative that can. If cut or tr will work, use that. If not, use sed. If not use awk.
c. The biggest sin of all, an abomination of a command that pipes together more than one of the above, awking the output of grep, for example.
While I agree with your principles, Bob is actually wrong – hostname does a lookup into the /etc/hosts file and may or may not give you the IP address of eth0. It depends on what you have in your hosts file. For example, I have a machine where “hostname -i” returns 127.0.0.1, simply because there was no name associated with the IP address of eth0 (192.168.0.16).
Grep/awk/sed pipes are costly in regards to system resources as you outlined, but sometimes you have to use them. What would be better is if there were a command that simply went “get-ip-address eth0″ and returned the IP, but I have not found one as of yet.
John,
Wow, you’re rather fun, aren’t you? Let’s dismiss beginners and overlook the intrinsic value of getting a look at how cut, grep and the others work for those folk [incl. me] and let’s just show how you’ve happily traded ‘my linux is better than yours’ for people skills.
Recommend “ip addr” for those with many VLAN IPs
“ip” is in the “iproute” package, “apt-get install iproute”
A small comment: in my ubuntu version 8.10, ifconfig gives inet adr,( and not inet addr).
Thanks for the tip.
eth0=($(ifconfig eth0 | grep “inet addr” | tr “:” ” “))
echo ${eth0[2]}
I am not agree with John,
with comments like this “Don’t be a dumb-ass and waste your RAM and CPU”.
It looks like you living in 19 century, you better group old man, this days RAM is cheap and CPU is big, and don`t jump on people who like to experiment with thinks.
Who like to experiment try this:
hostname -I | cut -d: -f2 | awk ‘{ print $1}’
or this
hostname -I | cut -d: -f2 | awk ‘{ print $2}’
even this will work
hostname -I | awk ‘{ print $1}’
or
hostname -I | awk ‘{ print $2}’
hostname -I works to
The ifconfig output in some system is localized and the awk version not work
very useful tips,
In my case, I want to list all my server IPs assigned to eth0, the ifconfig results something like
###
eth0 Link encap:Ethernet HWaddr 00:16:3E:D8:2B:BF
inet addr:127.0.0.1 Bcast:192.168.0.127 Mask:255.255.255.128
inet6 addr: fe80::216:3eff:fed8:2bbf/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4311554 errors:0 dropped:0 overruns:0 frame:0
TX packets:3027306 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:944036536 (900.3 MiB) TX bytes:6041030741 (5.6 GiB)
Interrupt:24
eth0:0 Link encap:Ethernet HWaddr 00:16:3E:D8:2B:BF
inet addr:192.168.0.2 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:24
eth0:1 Link encap:Ethernet HWaddr 00:16:3E:D8:2B:BF
inet addr:192.168.0.3 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:24
###
currently, for single IP, I can use this command
SERVERIP=`grep IPADDR /etc/sysconfig/network-scripts/ifcfg-eth0 | awk -F= ‘{print $2}’`
echo $SERVERIP
How to list all of my IPs?
Please reply to my email :)
Many thanks
I prefer doing it this way…
ifconfig eth0 | grep ‘inet addr:’ | cut -d”:” -f2 | cut -d” ” -f1
If hostname -i or hostname -I don’t give me what I want.