#!/bin/bash

config=/etc/ppp/options

mtu=$(sed -nr '/^mtu .*$/s/^mtu (.*)$/\1/p' $config)
echo current mtu is $mtu
items='false 400 false 500 false 1000 false 1500'
[ -z $mtu ] || items=$(echo $items | sed -r "s/false $mtu/true $mtu/")
echo items are $items
mtu=$(zenity --title='Choose MTU' --list --radiolist --text='' --column='' --column='' $items)
[ -z $mtu ] || { echo new mtu is $mtu; sed -ri "s/^#?mtu .*$/mtu $mtu/" $config; }
sudo /sbin/ifconfig ppp0 mtu $mtu
