= RRDtool =

You want to fetch the 15 minute average data for the last hour.  You might try

{{{
rrdtool fetch data.rrd  AVERAGE -r 900 -s -1h
}}}

Then convert time epoch time to human readable
{{{
#!sh
[krit@mini tmp]$ date -d @1629298800
Wed 18 Aug 2021 10:00:00 PM +07
}}]