Find interface in all namespaces by mac address

find_if_by_mac.sh

#!/bin/bash

# usage: ./find_if_by_mac.sh d4:3a:65:08:13:7e

function get_if_name() {
    name=`echo "$1" | awk '{print $2}' | sed 's/:$//'`
    echo $name
}

mac=$1
match=`ip --oneline -f link a | grep $mac`
if [[ $? = "0" ]]; then
    echo "Found $mac in default namespace"
    ip link show `get_if_name "$match"`
    exit 0
fi

ns_arr=`ip netns | awk '{print $1}'`
for ns in ${ns_arr[@]}; do
    match=`ip netns exec $ns ip --oneline -f link a | grep $mac`
    if [[ $? = "0" ]]; then
        echo "Found $mac in namespace $ns"
        ip netns exec $ns ip link show `get_if_name "$match"`
        exit 0
    fi
done

echo "Not found"