[rrd-users] weird behaviour of rrd graph

Alex van den Bogaerdt alex at vandenbogaerdt.nl
Wed Sep 29 22:25:05 CEST 2010

> Anyway, regarding the modulo trick - i`m not sure if i got that right
> You mean like this ?
> export now=$(( `date +"%s"` - $((`date +"%s"` % 21600)) ))
> rrdtool .... --start end-1y  --end $now ....

There will be shortcuts.  For instance, if your shell uses integer 
calculations (probably it does), try:

rrdtool ... --end $((`date +%s` / 21600 * 21600)) ...

Or, if you want to have some logging available not just for yourself but 
also for others, so that the problem can be reproduced, export now as you 
do, combined with the shortcut I proposed, and echo the entire rrdtool 
command line to a logfile ( echo rrdtool ... --end $now ... >> 
/tmp/rrd.txt )

If this actually makes a difference, it could be that all your graphs are in 
the undesired way. If so, subtract an hour or so from the date.

Keep us posted please! 

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