Use nmap to find open ports fast and then run a detailed scans on the returned ports

nmap_fast.sh

#!/bin/bash

# Use nmap to find open ports fast and then run a detailed scans on the returned ports

if [ -z "$1" ]
  then
    echo "__nmap_fast__"
    echo "Usage: ./nmap_fast TARGET_HOSTNAME"
fi
TARGET_HOSTNAME=$1
nmap -vv -max-retries 0 --min-parallelism 4500 ${TARGET_HOSTNAME}  -p- \
| awk -F'[ /]' '/Discovered open port/{print $4}' \
| paste -s -d, - \
| xargs -I '{}' nmap -T4 -p {} -A ${TARGET_HOSTNAME}