example that creates a string of curl commands to sequentially check for wan ip.

seqcurl.sh

#!/bin/bash

prog=${0##*/}

errlog(){
    logger -i -s -t $prog -p error "$2"
    [ $1 -gt 0 ] && exit $1
}

infolog(){
    logger -i -t $prog -p info "$1"
}

# Check multiple api endpoints sequentially.
ip_urls=(
    "https://ipv4.icanhazip.com"
    "https://api.ipify.org"
    "https://ifconfig.me"
    "https://bot.whatismyipaddress.com"
    "https://ipinfo.io/ip"
    "https://ipecho.net/plain"
)

# we use -s to suppress errors and -f to "fail".
ip_cmd='curl -sf --dns-servers 1.1.1.1'

ip=$(eval \
   $(echo ${ip_urls[@]} \
   | sed -e "s/\s/ || ${ip_cmd} /g;s/^/${ip_cmd} /"))

if [ -z "$ip" ]; then
    errlog 1 "External IP not found"
else
    infolog "Found external IP: $ip"
fi