nmon is short for Nigel's Performance Monitor It either shows you the stats on-screen updating once a second or saves the data to a CSV file for later analysis and graphing. For details see the homepage ==> http://nmon.sourceforge.net
Please use the latest version.
The new version "njmon" outputs JSON format that a lot of tools use these days. It integrates well with saving data directly to InfluxDB and graphing with Grafana.