temp sensors and mrtg

Temperature monitoring using openbsd's sensor framework and mrtg.

1. Locate sensors on main board:

   $ dmesg | grep lm
   lm0 at isa0 port 0x290/8: LM79

2. Locate number of CPU temperature sensor:

   $ sysctl hw.sensors | grep temp
   hw.sensors.7=lm0, Temp1, temp, 36.00 degC / 96.80 degF

3. Write a simple script for passing temperature to mrtg:

   #!/bin/sh
   sysctl hw.sensors.7 | awk '{ print $4 }'
   sysctl hw.sensors.7 | awk '{ print $4 }'

4. Add the following lines to your mrtg config:

   Target[Temp1]: `/root/temp.sh`
   MaxBytes[Temp1]: 70
   Options[Temp1]: gauge, noinfo, nopercent
   YLegend[Temp1]: Celsius
   LegendI[Temp1]: Temp
   LegendO[Temp1]: Temp
   Title[Temp1]: CPU temp
   ShortLegend[Temp1]: C
   PageTop[Temp1]: <h1>CPU temp</h1>

5. Have fun!