There is a new graphing feature which allows you to specify events that should be displayed in your graphs. These events are simply a list of points in time at which something of interest occurred.
For instance, one could create a plain text file in the graphs directory called events.txt containing these lines:
2001/02/10 1538 added support for events to FlowScan graphs
2001/02/12 1601 allowed the events file to be named on make command line
Then to generate the graphs with those events included one might run:
$ make -f graphs.mf events=events.txt
This feature was implemented using a new script called event2vrule that is supplied with FlowScan. This script is meant to be used as a ``wrapper'' for running rrdtool(1), similarly to how one might run nohup(1). E.g.:
$ event2vrule -h 48 events.txt rrdtool graph -s -48h ...
That command will cause these VRULE arguments to be passed to rrdtool, at the end of the argument list:
VRULE:981841080#ff0000:2001/02/10 1538 added support for events to FlowScan graphs
VRULE:982015260#ff0000:2001/02/12 1601 allowed the events file to be named on make command line