Show free memory.
$ free -ht total used free shared buffers cached Mem: 3.9G 3.8G 32M 96K 97M 1.1G -/+ buffers/cache: 2.6G 1.2G Swap: 1.0G 61M 962M Total: 4.9G 3.9G 995M
- total - physical memory
- cached - memory used to speed up operations. e.g. file read-write operations. This can be used by an application.
- buffers - Temporary memory to help some processes. (e.g. file meta data).
- In the first line used includes buffers + cached.
- In the second line used only includes memory used by applications.