Hi,
i want to tell you about a task manager for Linux system ( from terminal ).
The most famous is top, but if you want a different graphical for top you can use htop.
it is simply to get, on your terminal :
sudo apt-get install htop
then you can type on terminal htop and you can see another face of top.
it is simply to get and, for my opinion, it is simply to use and retrieve information about your system.
Thanks.