libstatgrab is a library that provides cross platform access to statistics about the system on which it's run. It's written in C and presents a selection of useful interfaces which can be used to access key system statistics. The current list of statistics includes CPU usage, memory utilisation, disk usage, process counts, network traffic, disk I/O, and more.

On a Debian system install the package as usual:

apt-get install saidar

and then run:

saidar