How can I graph a line with old data?

[misipino]

I need to compare the values of the current day with the values of the previous days of the week.
Using the command "rrdtool fetch" the answer is a type number:

1266407100: 3.3986666667e +01


This does not seem a valid value for Cacti.

How can I make it a valid number for Cacti?

Anybody know a script that makes the extraction of data from an rrd file and submit it as an integer?

Thx

[gandalf]

Do you only request a single data point?
Or is the SHIFT function the solution? Please see http://www.vandenbogaerdt.nl
R.

[misipino]

the problem is: I can read a value in RRD files and send the result as output?
That way I could import the output in a new RRD

[gandalf]

the problem is: I can read a value in RRD files and send the result as output?
That way I could import the output in a new RRD

This is surely possible. But still I do not understand what you want to achive. And I have an ugly feel, that you might not go for the easiest way ...
R.

[misipino]

Thank you for support.
I will try to explain better.

I want to have a graph showing two lines (A and B).
The first line (A) is the data in real time, the second line (B) is the data observed seven days before the same hour.
The value A is detected by a getSnmpdata and recorded in the file lineA.rrd and this works well.
The value B should read the file lineA.rrd for the value recorded 7 days before.

Thanks

[gandalf]

Well, fine. That's the perfect use case for SHIFT. See the explanation at the web site I advertised above. Unfortunately, this is not yet supported by current 087; but this will be supported by 088; the code is already in. 088 is NOT yet in beta state. So if you need a solution now, this turns out to be a problem.
R.

[misipino]

Right, the example given in the link is just my case, of course, all integrated into cacti.
I thought I crare invoked through a script that cacti could give as output the value recorded in a file rrd.
For example:

#/bin/bash!
value_b=0

value_b='rrdtool fetch lineA.rrd AVERAGE -s -7d -e -7d`

echo value_b

But the output 1266407100: 3.3986666667e +01 don't seem valid for cacti.

Wating full integration with cacti and not 'possible, in your opinion, use that or anyone script?

Grazie

[gandalf]

But the output 1266407100: 3.3986666667e +01 don't seem valid for cacti.

Simply strip out the "3.3986666667e +01" last number only
R.

[misipino]

This is the script I used.

#!/bin/sh

number=0

number=`rrdtool fetch /var/www/html/cacti/rra/lineA.rrd LAST -s -1d -e -1d`

echo `expr "$number" : '.*\(................\)'`

Output is a value to capture with datasource.

Thanks to Gandalf

[TheWitness]

I would so something like:

Code: Select all

echo $number | awk -F: '{print $2}' | tr -d ' '

TheWitness