get CPU and Ram infos via bash

[jumbo125]

Hello

I want to get cpu and ram infos via bash command.

So i use this for temperature:

 

For the cpu usage i needed a long time to find a solution. now i found this:

echo $[100-$(vmstat 1 2|tail -1|awk '{print $15}')]

 

For the free ram usage, i will use 

free --mega

 

My question

Are this command correct? the cpu command line is really new for me...

 

does it takes a lot of ressources, if i use this commands every 2 seconds to get a real time listening? i need to write it in a database to get a graphical solution.

 

Thank you for your help