Create a new sources list for use APT with an USB source mirror

add_usb_src_for_raspbian.sh

#!/bin/bash
# create a new sources list for use APT with this USB source mirror

USB_LIST=/etc/apt/sources.list.d/usb_source.list

# check root level
if [ $EUID -ne 0 ]
then
    echo "This script must be run as root" 1>&2
    exit 1
fi

# auto-detect USB source directory 
script_root=$(dirname `realpath $0`)
usb_root=$(realpath $script_root/..)
echo "detect USB source directory: $usb_root"

# check USB_LIST already exist
echo "check if $USB_LIST already exist..."
if [ -e "$USB_LIST" ]
then
    echo "can't add $USB_LIST: the file already exist"
    echo "launch sudo rm $USB_LIST to remove it"
    exit 2
else
    # build sources.list.raspbian for USB source
    echo "create and add $USB_LIST"
    echo "# auto-build APT sources list for update from a USB source" > $USB_LIST
    echo "deb file:$usb_root/raspbian/mirror/mirrordirector.raspbian.org/raspbian jessie main contrib non-free rpi" >> $USB_LIST
    echo "deb file:$usb_root/raspbian/mirror/archive.raspberrypi.org/debian jessie main ui" >> $USB_LIST
    echo "don't forget to launch sudo apt-get update to refesh apt index"
    exit 0
fi