Script that return a list of running Vagrant machine (IP HOSTNAME), so you can copy and paste it on your /etc/hosts

vagrant-hosts.sh

#!/bin/bash

interface="eth0"
hosts=`vagrant status | grep running | awk '{print $1}'`

if [ `echo ${hosts} | wc -w` -gt '0' ]
then
    for host in ${hosts}
    do 
        ip=`echo "ip a sh dev ${interface} | grep 'inet ' | sed 's/\// /g'" | vagrant ssh ${host} | awk '{print $2}'`
        echo -e "${ip}\t ${host}"
    done
else
    echo "There are no machines running"
fi