[rrd-users] Invalid RPN -- why?

Alex van den Bogaerdt alex at ergens.op.het.net
Thu Dec 13 02:12:42 CET 2007

On Thu, Dec 13, 2007 at 02:07:08AM +0200, Gutza wrote:
> I get an "invalid rpn" error message for the following CDEF:
> CDEF:old=old_percent,user_percent,-,familiar_percent,-,robot_percent,-

Let's look at the stack:


Looking good.

> The actual error message I get is this:
> ERROR: invalid rpn expression in: old_percent,user_percent,-,familiar_percent,-,robot_percent,-
> What am I doing wrong?

Perhaps there's a typo in this RPN or in one of the DEFs or CDEFs ?

rrdtool create x.rrd DS:x:GAUGE:120:U:U RRA:AVERAGE:0:1:1

rrdtool graph /dev/null \
        DEF:x=x.rrd:x:AVERAGE \
        CDEF:x1=x \
        CDEF:x2=x \

ERROR: invalid rpn expression in: x,x3,-,x1,-

notice how I wrote the innocent looking 'x3' in that last CDEF instead
of using 'x2' as I should have.

I agree: it would help if rrdtool told us it was 'x3' that it couldn't
understand.  No, I'm not going to write the patch.

Alex van den Bogaerdt

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