[BASH] Get public IP address

mip

#!/bin/bash

S1='whatismyip.akamai.com'
S2='icanhazip.com'
S3='ifconfig.me'

IP=$(curl -sk $S1)
IP_regex='^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$'

if [[ ! $IP =~ $IP_regex ]]; then
    IP=$(curl -sk $S2)
    if [[ ! $IP =~ $IP_regex ]]; then
        IP=$(curl -sk $S3)
    fi
fi

if [[ $IP =~ $IP_regex ]]; then
    echo $IP | tr -d '[:space:]'
fi

You can also use my GIP, a CLI tool for NodeJS.