[rrd-users] Beginner question: "rrdtool.exe graph" started from windows shell does not produce any graph nor error message

Petr Lázňovský lazna at volny.cz
Wed Jan 8 15:41:26 CET 2014

Got it now, after studying documents again. Controlling rrdtool is more 'programming conditions' rather than 'run utility with a command and modify it`s behaviour by some non-mandatory parameters'. Something like difference between 'cut' and 'awk' utility for example.

For non-programming people like me, this could be crucial information and should be written on the top of page with bold font. I spent(waste) many hours with google to try understanding how this work. 

But how many non-programming people dealing with rrdtool..... Maybe you are right....

Anyway, thank you for help and comment.


BTW: I read in many documents (often more than 10 years old) so MRTG3 will be merged with rrdtool, is it still actual information?


>> I have read both manual and tutorial again and discovered missed parameter
>> "LINE1:traffic#xxxxxx"

>> It`s pitty the author hide this important sentence at the very end of
>> document: "You need at least one DEF and one LINE, AREA, GPRINT, PRINT
>> statement to generate anything useful"

>> Should I consider those parameters as a mandatory minimum? Without
>> AREA,GPRINT and PRINT, still got valid graph. Can someone explain me this?

> There is no such thing as a mandatory line or a mandatory area. And if you do
> not want a legend line from GPRINT then that too is just fine.  If you do
> not ask RRDtool to produce any output, it will not produce output. It did
> exactly what you asked it to do, so there's no error either.

> It's perfectly fine to just draw a line without any legend. You'd need a DEF
> and a LINE.  Also fine is a legend without a line; you'd need a DEF and a
> GPRINT command.  Whether or not that's useful, is your decision.

> It's perfectly fine to just have a DEF and a PRINT.  No graph created, there
> will be only a number returned to the calling process.  Again, that is not an
> error condition, it is what you ask RRDtool to do.

> If you did not yet 'get it' yet, maybe you paced through the tutorial too
> fast.

> Summarized:
> get data:  DEF
> massage data:  CDEF
> output data: LINE, AREA, PRINT, GPRINT.  Choose zero or more.

> and you should look at XPORT, which is not covered in the tutorial because
> the tutorial was written in the v1.0 era of rrdtool and XPORT came later.

> HTH,
> "the author"

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