sigh. i need to add an additional data source to my rrd file. in my specific case, a new temperature probe; probe 7. i also managed to forget the specifics of the rrd. that's okay. # rrdtool info /var/stats/rrd/envmon/temp.rrd filename = "temp.rrd" rrd_version = "0003" step = 60 last_update = 1388770922 ds[probe1].type = "GAUGE" ds[probe1].minimal_heartbeat = 300 ds[probe1].min = 5.5000000000e+01 ds[probe1].max = 9.5000000000e+01 cool. we have the step and type and heartbeat and min and max. # cpan install RRD::Simple script... #!/usr/local/bin/perl use strict; use RRD::Simple (); my $rrd = RRD::Simple->new(); my $rrdfile=$ARGV; my $source=$ARGV; my $type=$ARGV; chomp($type); $rrd->add_source($rrdfile, $source => $type); ... script usage: ./addSource.pl file.rrd ds GAUGE e.g.: # ./addSource.pl /var/stats/rrd/envmon/temp.rrd probe7 GAUGE:300:55:95that wasn't so hard.