how to export realm database, full article : http://medyo.github.io/2016/browse-populate-and-export-realm-database-on-android/

extract_realm_database_android.sh

#!/bin/sh
ADB_PATH="/Users/medyo/Library/Android/sdk/platform-tools"
PACKAGE_NAME="com.mobiacube.elbotola.debug"
DB_NAME="default.realm"
DESTINATION_PATH="/Users/Medyo/Desktop/"
NOT_PRESENT="List of devices attached"
ADB_FOUND=`${ADB_PATH}/adb devices | tail -2 | head -1 | cut -f 1 | sed 's/ *$//g'`
if [[ ${ADB_FOUND} == ${NOT_PRESENT} ]]; then
	echo "Make sure a device is connected"
else
    ${ADB_PATH}/adb shell "
    	run-as ${PACKAGE_NAME} cp /data/data/${PACKAGE_NAME}/files/${DB_NAME} /sdcard/
		exit
	"
	${ADB_PATH}/adb pull "/sdcard/${DB_NAME}" "${DESTINATION_PATH}"
	echo "Database exported to ${DESTINATION_PATH}${DB_NAME}"
fi

I got error message, cp: /sdcard: Permission denied

I find a solution, http://stackoverflow.com/a/18472135/2227031
This is my revision: https://gist.github.com/jk2K/a66ed67b252b880824b32dd4952d1b39