shell script to tell if an android application is publicly available on googleplay

list_private_apps.sh

#!/bin/sh -e
set -o nounset

PLAY_URL="https://play.google.com/store/apps/details?id="
ret="private_app_list.txt"

if ! [ $# -eq 1 ]; then
    echo "Error: appname not provided!";
    exit
fi

appname="$1"
#echo "Checking ${appname} ..."
curl "${PLAY_URL}${appname}" -I | if egrep -i '404 not found'; then
        echo "${appname} is not in play store!";
        echo "${appname}" >> "$ret";
    fi