Capture output of a bash command, parse it and store into different bash variables

Question

Explanation:

I have a small bash script which simply runs any Linux command (e.g. say ifconfig)

The typical output of ifconfig is something like this:

eth0      Link encap:Ethernet  HWaddr 30:F7:0D:6D:34:CA
          inet addr:10.106.145.12  Bcast:10.106.145.255  Mask:255.255.255.0
          inet6 addr: fe80::32f7:dff:fe6d:34ca/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1104666 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2171 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:444437904 (423.8 MiB)  TX bytes:238380 (232.7 KiB)

lo        Link encap:Local Loopback 
          inet addr:127.0.0.1  Mask:255.255.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:15900 errors:0 dropped:0 overruns:0 frame:0
          TX packets:15900 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:467306 (456.3 KiB)  TX bytes:467306 (456.3 KiB)

Now what most people usually do is store the entire output into a file/variable and parse based on that. I however want to know if there is anyway that I could put specific parts of the output in more than one variable (say a bash variable called ${IPETH0} to carry the IP address 10.106.145.12 from eth0 and ${IPLO} to carry the IP address 127.0.0.1 from lo in the above example without running ifconfig command twice).

Something like what tee command does with the input but I want to do this for the output and store the output into 2 or more variables in one go. Any ideas?

Answer 1

$ read IPETH0 IPLO <<< $(ifconfig | awk '/inet[[:space:]]/ { print $2 }')
$ echo "${IPETH0}"
192.168.23.2
$ echo "${IPLO}"
127.0.0.1

This assumes the order of the eth0 and lo interfaces, but it shows the basic idea.

Answer 2

You can use awk and bash arrays:

arr=( $(awk -F ':' '$1 == "inet addr"{sub(/ .*/, "", $2); print $2}' < <(ifconfig)) )

Then you can do:

read IPETH0 IPLO <<< ${arr[@]}

Answer 3

you can read each line of ifconfig and set variables :

while read l1 ;do 
   if [[ $l1 =~ inet ]];then     
      set -- $l1 
      echo  "ip is  $2  " 

   fi
done < <(ifconfig)