Memory Usage in LINUX [duplicate]

See: Help! Linux ate my RAM!

Answered in other questions, but the short answer is that what you want for used memory is the following number from the output of the command free:

-/+ buffers/cache: 557896

I commonly run into this problem on various UXIX flavors. Unless otherwise configured, they buffer everything they read. Free memory goes to near zero eventually, and will stay there forever. Unless the memory is used for something else, all the startup scripts remain buffered forever.

Administrators who don't understand that most buffers are relatively memory may refuse to increase the size of memory structures. This can (severely) degrade performance of some applications.