I wanted to know the concept of free –m command as there are different rows of Mem, -/+ buffers/cache & Swap in the output. As an example, it is showing 195 as free Mem in my server but 13850 in the free section of the -/+ buffers/cache row. The output needs in depth knowledge of the different parameters of the command.

I hope, my question is clear.

Please revert with the reply to my query.

Regards

             total       used       free     shared    buffers     cached
Mem:          3816       3569        247          0        118       2397
-/+ buffers/cache:       1053       2763
Swap:         3823         13       3810

Thanks for your answer. I wanted to add something, if we add 118 to the total of 2397 & 247, it would be 2762 which is very near the free memory on line 2, 2763. Please confirm on this.

Also, as per your answer, the architecture of Linux is to utilize all the memory on the system.

the line +/- buffers/cache basically shows the memory used and free without taking into account how much is used for buffers or cache.

This is because cached memory is not actually used memory, it is information that is stored for quick retrieval if requested again from previous operations but dumped straight away if memory is required to be written to. This process makes the system run quicker as queries are using data stored on RAM instead of hard disk which is obviously a much quicker process.

So yes, top line free + cached = free on 2nd line