January 24, 2017

Get IP Address In A Script

Recently needed a good way to fetch the IP address of each interface within a script. Tried things like:

ifconfig  | grep 'inet addr:'| grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print $1}'

1	ifconfig \| grep 'inet addr:'\| grep -v '127.0.0.1' \| cut -d: -f2 \| awk '{ print $1}'

and

/sbin/ifconfig | sed -n '2 p' | awk '{print $3}'

1	/sbin/ifconfig \| sed -n '2 p' \| awk '{print $3}'

But this is fairly ugly. So I tried:

hostname -I

1	hostname -I

This gives a list of IP addresses but they are un-ordered so I can’t guarantee which address goes with which interface. Here’s one using “ip addr”:

ip=$(ip -f inet -o addr show eth0|cut -d\  -f 7 | cut -d/ -f 1)

1	ip=$(ip -f inet -o addr show eth0\|cut -d\ -f 7 \| cut -d/ -f 1)

Still very messy. Finally, found the “ifdata” command which is part of the “moreutils” package. First make sure “moreutils” is installed with:

yum -y install moreutils

1	yum -y install moreutils

Now you can query for a wide range of different information:

Usage: ifdata [options] iface
     -e   Reports interface existence via return code
     -p   Print out the whole config of iface
    -pe   Print out yes or no according to existence
    -pa   Print out the address
    -pn   Print netmask
    -pN   Print network address
    -pb   Print broadcast
    -pm   Print mtu
    -ph   Print out the hardware address
    -pf   Print flags
    -si   Print all statistics on input
   -sip   Print # of in packets
   -sib   Print # of in bytes
   -sie   Print # of in errors
   -sid   Print # of in drops
   -sif   Print # of in fifo overruns
   -sic   Print # of in compress
   -sim   Print # of in multicast
    -so   Print all statistics on output
   -sop   Print # of out packets
   -sob   Print # of out bytes
   -soe   Print # of out errors
   -sod   Print # of out drops
   -sof   Print # of out fifo overruns
   -sox   Print # of out collisions
   -soc   Print # of out carrier loss
   -som   Print # of out multicast
  -bips   Print # of incoming bytes per second
  -bops   Print # of outgoing bytes per second

Usage: ifdata [options] iface

-e Reports interface existence via return code

-p Print out the whole config of iface

-pe Print out yes or no according to existence

-pa Print out the address

-pn Print netmask

-pN Print network address

-pb Print broadcast

-pm Print mtu

-ph Print out the hardware address

-pf Print flags

-si Print all statistics on input

-sip Print # of in packets

-sib Print # of in bytes

-sie Print # of in errors

-sid Print # of in drops

-sif Print # of in fifo overruns

-sic Print # of in compress

-sim Print # of in multicast

-so Print all statistics on output

-sop Print # of out packets

-sob Print # of out bytes

-soe Print # of out errors

-sod Print # of out drops

-sof Print # of out fifo overruns

-sox Print # of out collisions

-soc Print # of out carrier loss

-som Print # of out multicast

-bips Print # of incoming bytes per second

-bops Print # of outgoing bytes per second

So here are some examples:

[root@host]# ifdata -pa eth0
10.210.160.53

[root@host]# ifdata -pa eth0
10.210.160.53

[root@host]# ifdata -pn eth0
255.255.224.0

[root@host]# ifdata -sip eth0
1622384587

[root@host]# ifdata -bops eth0
896