How to run apt-get update/install from behind a proxy

Hi I wrote this script to use apt-get behind a proxy , My password must change everymonth due to company policy's ,
This makes it easier to update, ( you can mayby use this script with cron to force a user to update the password on a specific date

Code:

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#!/bin/bash
echo "New Username:"
read usr
echo "New Password:"
read -s pass
echo "Proxy name or address:"
read name
echo "Proxy port:"
read port


http='Acquire::http::Proxy "http://'"${usr}"':'"${pass}"'@'"${name}"':'"${port}"'/";'
ftp='Acquire::ftp::Proxy "ftp://'"${usr}"':'"${pass}"'@'"${name}"':'"${port}"'/";'
https='Acquire::https::Proxy "https://'"${usr}"':'"${pass}"'@'"${name}"':'"${port}"'/";'


if [ -f /etc/apt/apt.conf ];
then
rm -r /etc/apt/apt.conf
fi
touch /etc/apt/apt.conf
echo $http >> /etc/apt/apt.conf
echo $ftp >> /etc/apt/apt.conf
echo $https >> /etc/apt/apt.conf

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