Mine

rrdtool graph $outpath/temperature.png -t 'theDude: temperatures' -v 'deg C' -w $width -h $height -A DEF:CPUTemp=$rrd_file:CPUTemp:AVERAGE CDEF:smoothed=CPUTemp,900,TREND DEF:MBTemp=$rrd_file:MBTemp:AVERAGE VDEF:temp1max=CPUTemp,MAXIMUM VDEF:temp1min=CPUTemp,MINIMUM VDEF:temp1avg=CPUTemp,AVERAGE VDEF:temp1last=CPUTemp,LAST VDEF:temp2max=MBTemp,MAXIMUM VDEF:temp2min=MBTemp,MINIMUM VDEF:temp2avg=MBTemp,AVERAGE VDEF:temp2last=MBTemp,LAST COMMENT:"              max           min            avg           last\\n" LINE1:CPUTemp#FF0000:"CPU    " GPRINT:temp1max:"%6.1lf deg C" GPRINT:temp1min:"%6.1lf deg C" GPRINT:temp1avg:"%6.1lf deg C" GPRINT:temp1last:"%6.1lf deg C\\n" LINE1:MBTemp#0000FF:"M/board" GPRINT:temp2max:"%6.1lf deg C" GPRINT:temp2min:"%6.1lf deg C" GPRINT:temp2avg:"%6.1lf deg C" GPRINT:temp2last:"%6.1lf deg C"