Looking for a PHP Script to delete all keys of the specified Redis database

Looking for a PHP Script to achieve the follows: We will set a cronjob to run the PHP Script. Delete all keys of the Redis database 0 (CLI command: redis-cli -n 0 FLUSHDB) if the free memory of the server is less than 1GB (CLI command: free -h) once the PHP Script run by the cronjob. Requiremnts: 1. We will upload the script to the same server of the redis, so the script should be run on the same server of the redis server 2. The PHP script should not be encrypted, so that we can modify the script ourselves System of the server: OS: debian Version: 8 (jessie)