grep eth0 /proc/net/dev | awk '{print $2}' | sed 's/eth0://g'

##</code><code>##

awk '/eth0/ {print $2}' /proc/net/dev | sed 's/eth0://g'

##</code><code>##

awk '/eth0/ {print gensub("eth0","","g",$2); }' /proc/net/dev'