Yesterday night, chatting with maop he ask about how to clean the memory in linux, I ask what about what he means about "cleaning", he said "free all the memory used by cach??????©", Well, in some way is a nice question that I make to myself some months ago, "Why is allways used all my RAM if I have 528MB?", google points me to some page wich solve my question: "Cache", yes, most of my RAM is used for cache, why?, well, is easier and faster for linux to load chunks of programs from the cache instead loading from the disk, so if you have firefox opened you can open a new window faster than the first time, even if you close firefox it will open faster.

Then, cleaning the cache is not a good idea, but, maybe you want to do it just to do it. Well, Cache is still there until Linux "thinks" that it will not be needed anymore (like swap pages) or when more resident memory is needed. Then you can

1. Wait until your cache is automaticly cleaned, or
2. Launch a memory eater program

The second is faster, but may slow down your system like a turtle, and if you don't take care it may crash your system. There is where raise another question : How to limit the memory usage per user?.

I use my "memory eater" program yesterday and I almost crash my system, as a single user!!, what if I where using a server with several users connected?. I mean, is there something like Quota but for RAM?.

If you want to check it compile this and run it as a single user: