Question: Hi I'm working on a small bash script that will scan lan every 5 minutes and get live host and then get theirs MAC addresses.

So far I have this:

```
nmap -sP -n -oG - 10.0.0.1-20 | grep "Up" | awk '{print $2}'

```

Which gives me ip addresses. Now I have to do something like

```
arp -an | grep 'ip'

```

but I'm new to bash and I don't know how :)

Answer: 
Here is a script that does exactly what you want:

```
#!/bin/bash

HOSTS=$(nmap -sP -n -oG - 192.168.1.1-10 | grep "Up" | awk '{print $2}')

for host in ${HOSTS}; do
  arp -an | grep ${host} | awk '{print $2 $4}'
done

```
Try using `arp-scan`, e.g:

```
sudo arp-scan --interface=wlan0 192.168.1.0/24

```