find_IF_using_MAC_addr

#!/bin/bash

# find_IF_using_MAC_addr
# 
# This script finds the network interface corresponding to a given MAC address.
# Usage: ./find_IF_using_MAC_addr <TARGET_MAC>
# 
# Arguments:
#   TARGET_MAC - The MAC address to search for.
#
# Output:
#   If a network interface with the specified MAC address is found, the script
#   outputs the name of the network interface and exits with a status code of 0.
#   If no matching interface is found, the script exits with a status code of 1.
#
# Example:
#   ./find_IF_using_MAC_addr xx:xx:xx:xx:xx:xx
#
# Maintainer:
#   Qucheng Jiang
# 

TARGET_MAC=$1

# get all interfaces
ALL_INTERFACES=$(ip link show | grep -Eo '^[0-9]+: [^:]+:' | cut -d' ' -f2 | tr -d ':')

# search for first interface with specific MAC address
for IFACE in $ALL_INTERFACES; do
    if [ -f /sys/class/net/$IFACE/address ]; then
        MAC=$(cat /sys/class/net/$IFACE/address)
        if [ "$MAC" == "$TARGET_MAC" ]; then
            echo $IFACE
            exit 0
        fi
    fi
done

exit 1