Transformando rapidamente variáveis em arrays

Exemplo: extraindo IP de uma interface de rede.

ifconfig eth0

wlx1cbfce6e75de: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.0.100  netmask 255.255.255.0  broadcast 192.168.0.255
        inet6 fe80::cf23:5845:2b78:1e85  prefixlen 64  scopeid 0x20
        ether 1c:bf:ce:6e:75:de  txqueuelen 1000  (Ethernet)
        RX packets 418333  bytes 94015853 (89.6 MiB)
        RX errors 0  dropped 4916  overruns 0  frame 0
        TX packets 4071471  bytes 431692317 (411.6 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

var00=$(ifconfig eth0); set $var00; echo "${6}"; echo "${18}"
192.168.0.100
1c:bf:ce:6e:75:de

Onde ${6} imprime o sexto elemento da array (endereço IP) e ${18} o décimo oitavo (endereço MAC).