This is a very useful command to release the memory without rebooting your system.
You can checked the memory usage first: And I ran `vmstat` to see more information about my machine. It shows more information about the usage.
There are many commands can help you check your machine's usage; please refer to this nice article: Linux Check Memory Usage.
I tried to kill some processes, but it doesn't help very much. What I really want is to quickly release the memory, and this command can simply release the memory for you:
$ sudo sync && sudo bash -c 'echo 3 > /proc/sys/vm/drop_caches';After released the memory: This is exactly what I searching for.