January 16, 2013, 2:50 PM — Here's how you can free up unused memory in Ubuntu or Linux Mint.
1. Open a terminal window.
2. Type in the following command, then hit Enter:
sudo sysctl -w vm.drop_caches=3
3. You can also use this command:
sudo sync && echo 3 | sudo tee /proc/sys/vm/drop_caches
For more, see the original article at the link below.