What is available and free memory in response of free command on Linux? [closed]
Modern operating systems go out of their way to keep as little memory free as possible. Memory that is free is actually harder to use because it has to be transitioned from free to in use. Memory that is already in use, that is, memory that is available but not free, can easily be switched to another use.
All this is normal. Free memory is wasted and does not make your system faster.
If you're thinking "but I want my memory free now so I can use it later", realize that this makes no sense. You can't save memory for later. A system with 4GB that uses 2GB today can't use 6GB tomorrow. You can use your memory both now and later. There is no tradeoff here -- using memory is free. The only alternative to using memory is wasting it. Why would you want your system to waste more memory?