[rrd-users] Concatenated VDEF and CDEF commands in a rrdtool graph cmd

[Rob Newman]

Hi there,

Does anyone know why this fails:

rrdtool graph /path/to/outputimage/rrd.png \
    --interlaced --imgformat PNG --end 1289434618 --start 1286756217 \
    --width 600 --height 200 --title 'TEST' \
    DEF:dt=/path/to/dt.rrd:dt:AVERAGE \
    VDEF:dtfoo=dt,MAXIMUM \
    CDEF:dtmaxdiff=dtfoo,16,- \
    LINE1:dtmaxdiff#990000:'TESTFOO' \
    GPRINT:dt:LAST:'Latest value for TESTFOO\: %4.0lf%s\j'

The output I get from rrdtool is:

ERROR: rpn expressions without DEF or CDEF variables are not supported

If I try and add backslashes to the path (a la http://www.mrtg.org/rrdtool/doc/rrdgraph_rpn.en.html, note between the VDEF and CDEF rpn command there is not a carriage return anymore, just whitespace and a backslash):

rrdtool graph /path/to/outputimage/rrd.png \
    --interlaced --imgformat PNG --end 1289434618 --start 1286756217 \
    --width 600 --height 200 --title 'TEST' \
    DEF:dt=/path/to/dt.rrd:dt:AVERAGE \
    VDEF:dtfoo=dt,MAXIMUM \ CDEF:dtmaxdiff=dtfoo,16,- \
    LINE1:dtmaxdiff#990000:'TESTFOO' \
    GPRINT:dt:LAST:'Latest value for TESTFOO\: %4.0lf%s\j'

I now get the output:

ERROR: Could not make sense out of ' CDEF:dtmaxdiff=dtfoo,16,-'

What I want is to find the maximum value for the data set ('dtfoo = dt,MAXIMUM'), then take that value and subtract 16 from it (dtmaxdiff = dtfoo,16,-), then plot that value.

Any ideas why both of these fail?

Thanks in advance,
- Rob
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