Hi,
I am a New guy installed SuiteCRM Bitnami Stack on an Ubuntu 18.04 LTS.
I try to run php -f cron.php for a test but I have get the message below :
Could anyone can help me to solve it.
Could anyone can help me to solve it.
Hi, welcome to the Community! 
And is the app running normally, I mean, can you use SuiteCRM from the UI?
It seems the database connection isn’t working, at least form command-line-PHP (CLI), which is different from web-server-PHP.
You might need to install the PHP mysqli, module, or perhaps it is installed and all that is missing is to enable it from your php.ini.
Use his command to get to the correct php.ini:
php -i | grep php.ini