Old script to start IIJmio's IPv6

iij-ipv6-up.sh

#!/bin/sh

sed -i -e "/nameserver 2001:240:.*$/d" /etc/resolv.conf

iter=0
until nc ipv6a.2iij.net 1723 < /dev/null > /dev/null 2>&1
do
	iter=$(expr $iter + 1)

	if [ $iter -gt 30 ]
	then
		exit 1
	fi

	sleep 1
done

pppd call iij-ipv6

iter=0
until ip addr show ppp128 scope global 2>&1 | grep global > /dev/null
do
	iter=$(expr $iter + 1)

	if [ $iter -gt 30 ]
	then
		exit 1
	fi

	sleep 1
done

echo -e "nameserver 2001:240::13\nnameserver 2001:240::14\n$(cat /etc/resolv.conf | grep nameserver)" > /etc/resolv.conf

Rewritten with "until"