How to Set the Proxy for APT on Ubuntu 18.04

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

#!/bin/bash

set -eu -o pipefail # fail on error and report it, debug all lines

sudo -n true
test $? -eq 0 || exit 1 "you should have sudo privilege to run this script"

echo installing the must-have pre-requisites
while read -r p ; do sudo apt-get install -y $p ; done < <(cat << "EOF"
    perl
    zip unzip
    exuberant-ctags
    mutt
    libxml-atom-perl
    postgresql-9.6
    libdbd-pgsql
    curl
    wget
    libwww-curl-perl
EOF
)

echo installing the nice-to-have pre-requisites
echo you have 5 seconds to proceed ...
echo or
echo hit Ctrl+C to quit
echo -e "\n"
sleep 6

sudo apt-get install -y tig

#update
sudo apt-get update || true && sudo apt-get upgrade -y || true

#dependencies 
sudo apt-get install gnupg1

#add webmin repo
echo "deb http://download.webmin.com/download/repository sarge contrib" | sudo tee /etc/apt/sources.list.d/webmin.list

#add pgp key
sudo mkdir -p /etc/apt/keyrings
wget -qO- http://www.webmin.com/jcameron-key.asc | gpg --dearmor | sudo tee /etc/apt/keyrings/webmin.gpg > /dev/null

echo "deb [signed-by=/etc/apt/keyrings/webmin.gpg] http://download.webmin.com/download/repository sarge contrib" | sudo tee /etc/apt/sources.list.d/webmin.list


#install Webmin
sudo apt-get update || true && sudo apt-get upgrade -y || true
sudo apt-get install webmin -y || true

#enable firewall
sudo ufw allow 10000

#to use webman navigate to https://your_server_ip:10000 in web browser 
#replace "your_server_ip" with servers ip.