Download an APK file and print the package and signature.

package_name_and_sign.sh

#!/bin/sh
# package_name_and_sign.sh https://xxx.com/xxx.apk
rm -rf tmp
mkdir tmp
cd tmp/
wget --no-check-certificate $1 -O tmp.rar

echo "Package Name:"
$ANDROID_HOME/build-tools/28.0.2/aapt dump badging tmp.rar | grep package:\ name	# Find Package Name

unzip -qq tmp.rar
result="$(/Library/Java/JavaVirtualMachines/jdk1.8.0_40.jdk/Contents/Home/bin/keytool -printcert -file META-INF/*.RSA)"
empty=""
result="${result//[:]/$empty}"  # Remove ':' 

echo "Signature:"
echo "${result}" | tr '[:upper:]' '[:lower:]' | grep md5 #find md5 signature