The free command is used in LINUX to give stats about MEMORY/SWAP usage.
Others may have blogged about this simple command before but most important is HOW to understand & interpret the results.
Beginners might be confused the first time they run the command.
A little theory on MEMORY USAGE in LINUX: “In Linux, unused memory is wasted memory”
That’s why memory is used for caching whenever possible.
I got the following nice illustration from Linux Performance and Tuning Guidelines by IBM (RedPaper)
The amount of FREE MEMORY is calculated by the formula:
FREE = free + buffers + cached
Another website dedicated completely to the FREE command is :