[rrd-users] print a variable in the COMMENT field?

[Alex van den Bogaerdt]

On Wed, Feb 20, 2008 at 08:36:00AM -0700, Matthew Tice wrote:
> Hello, I'm wondering if it is possible to print a variable in the COMMENT:
> field.  I have a setup like this:
>        TITLE Freezer Temperature
>        YAXIS Degrees Kelvin
>        DEF:tl=freezer.rrd:freezerf:AVERAGE
>        CDEF:k2c=tl,273.15,-
>        AREA:tl#@COLOR@:Temperature
>        COMMENT:\n
>        GPRINT:tl:LAST:Temperature\: %2.1lf (cur)
>        GPRINT:tl:MAX:\: %2.1lf (max)
>        GPRINT:tl:MIN:\: %2.1lf (min)
>        GPRINT:tl:AVERAGE:\: %2.1lf (avg)\n
> 
> 
> I'd like to take that variable k2c and print it's value on the COMMENT
> line.  Is this at all possible?


k2c is not really a variable, it is more like an array of variables.
You would need a print statement (such as those for tl) anyway.

And now the answer: yes, it is possible, but not from rrdtool itself.


Consider:

        DEF:tl=freezer.rrd:freezerf:AVERAGE
        CDEF:k2c=tl,273.15,-
        PRINT:k2c:AVERAGE:%2.1lf

called from a script. This script catches the output, into a
variable, and uses that in the next RRDtool command:

        DEF:tl=freezer.rrd:freezerf:AVERAGE
        CDEF:k2c=tl,273.15,-
        AREA:tl#@COLOR@:Temperature
        COMMENT:${YOURVARGOESHERE}\n
        GPRINT:tl:LAST:Temperature\: %2.1lf (cur)
        GPRINT:tl:MAX:\: %2.1lf (max)
        GPRINT:tl:MIN:\: %2.1lf (min)
        GPRINT:tl:AVERAGE:\: %2.1lf (avg)\n

If this means it is possible _for_you_ in _your_ setup, I cannot tell.
But it is possible.

-- 
Alex van den Bogaerdt
http://www.vandenbogaerdt.nl/rrdtool/