Example pipeline that adds an absolute timestamp and converts to CSV.

    sample-timestamp --input log.txt --relative-name now | \
      sample-convert --output-format csv > log.csv  

Example input:

    analog=251, dry=0, pumping_water=0, last_watering_started=234, last_watering_stopped=235, now=346

Example output:

    now,analog,dry,pumping_water,last_watering_started,last_watering_stopped,timestamp
    346,251,0,0,234,235,1425594335
    347,249,0,0,234,235,1425594336
    348,248,0,0,234,235,1425594337
    349,245,0,0,234,235,1425594338

Combining with rrdtool

    rrdtool create test.rrd --step 1  \ 
        --start 1425593989 \
        DS:analog:GAUGE:600:U:U \
        RRA:AVERAGE:0.5:1:864000 \
        RRA:AVERAGE:0.5:60:14400

Inserting values

    sample-timestamp --input log.txt --relative-name now | \
        sample-convert --output-format rrd --fields analog | \
        xargs rrdtool update test.rrd

Graphing values

    rrdtool graph graph.png --width 1024 --height 512 \
        --start 1425593989 --end 1425991529 \
        DEF:a=test.rrd:analog:AVERAGE LINE2:a#FF0000