Detecting if a proxy is used for the active Network Location on a specific adaptor

.profile

if [ "`networksetup -getwebproxy 'USB Ethernet' | awk {'print $2'} |  head -n 1 |  tr -d ' '`" = "Yes" ]; then
  export HTTP_PROXY=`networksetup -getwebproxy 'USB Ethernet' | awk {'print $2'} | awk {'getline l2; getline l3; print "http://"l2":"l3'} | head -n 1`
  export HTTPS_PROXY=$HTTP_PROXY
  export ALL_PROXY=$HTTP_PROXY
  export http_proxy=$HTTP_PROXY
  export https_proxy=$HTTP_PROXY
  export all_proxy=$HTTP_PROXY
  echo "Using $HTTP_PROXY as a Proxy"
else
  unset HTTP_PROXY
  unset HTTPS_PROXY
  unset ALL_PROXY
  unset http_proxy
  unset https_proxy
  unset all_proxy
fi