Here are two methods to check memory usage:
Top command : It provides a dynamic, real-time view of the current state of the system. You can view system information and process information, including up-time, average load, running tasks, number of logged-in users, and RAM usage. Also, you can view the processes that your users are running/using on your server.
Free command : Top command, however, can sometimes be too much for your purposes. If all you need is to see how much memory is free and used on your system, you can use the free command.
