How can I find out how much memory my Linux is using?

From a command shell, use the “concatenate” command: cat /proc/meminfo for memory usage information. You should see a line starting MemTotal:  see below.  ie: MemTotal: 15733472 or 15GB, MemFree: and MemAvailable: This is the total memory Linux thinks it has available to use.           You can also use commands free -…