X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=doc%2Frrdfetch.pod;h=16bee22a8b9c13f78ebba7f9b607ef2d6fc81867;hb=09fa22ce43438f77625e759d7b29d8ae6bc56084;hp=0b57340ca0c0721c3b76fda6784ac08c70b2c8ab;hpb=d53241d45f61489bd1bd2fb1aab5e6183db6009d;p=rrdtool.git diff --git a/doc/rrdfetch.pod b/doc/rrdfetch.pod index 0b57340..16bee22 100644 --- a/doc/rrdfetch.pod +++ b/doc/rrdfetch.pod @@ -1,8 +1,6 @@ =head1 NAME -rrdtool fetch - fetch data from an rrd. - -=for html
PDF version.
+rrdfetch - Fetch data from an RRD. =head1 SYNOPSIS @@ -17,7 +15,7 @@ The B function is normally used internally by the graph function, to get data from Bs. B will analyze the B and will try to retrieve the data in the resolution requested. The data fetched is printed to stdout. I<*UNKNOWN*> data is often -represented by the string "NaN" depending on your OSs printf +represented by the string "NaN" depending on your OS's printf function. =over 8 @@ -54,7 +52,7 @@ end time. =head2 RESOLUTION INTERVAL -In order to get rrdtool to fetch anything other than the finest resolution RRA +In order to get RRDtool to fetch anything other than the finest resolution RRA B the start and end time must be specified on boundaries that are multiples of the wanted resolution. Consider the following example: @@ -99,18 +97,21 @@ So, if time now is called "t", In e.g. bash this could look as: - TIME=$(date +%s); RRDRES=900; rrdtool fetch subdata.rrd AVERAGE -r $RRDRES \ - -e $(echo $(($TIME/$RRDRES*$RRDRES))) -s e-1h + TIME=$(date +%s) + RRDRES=900 + rrdtool fetch subdata.rrd AVERAGE -r $RRDRES \ + -e $(echo $(($TIME/$RRDRES*$RRDRES))) -s e-1h -Or in perl: +Or in Perl: - perl -e '$ctime = time; $rrdres = 900; system "rrdtool fetch subdata.rrd AVERAGE \ - -r $rrdres -e @{[int($ctime/$rrdres)*$rrdres]} -s e-1h"' + perl -e '$ctime = time; $rrdres = 900; \ + system "rrdtool fetch subdata.rrd AVERAGE \ + -r $rrdres -e @{[int($ctime/$rrdres)*$rrdres]} -s e-1h"' =head2 AT-STYLE TIME SPECIFICATION -Apart from the traditional I, rrdtool does also +Apart from the traditional I, RRDtool does also understand at-style time specification. The specification is called "at-style" after Unix command at(1) that has moderately complex ways to specify time to run your job at. The at-style specification @@ -148,7 +149,7 @@ Finally, you can use words B, B, or B as your time reference. B refers to the current moment (and is also a default time reference). B (B) can be used to specify time relative to the start (end) time for those tools that use these -categories (rrdfetch, rrdgraph). +categories (B, L). Month and weekday names can be used in their naturally abbreviated form (e.g., Dec for December, Sun for Sunday, etc.). The words B, @@ -248,10 +249,8 @@ I<931225537> -- 18:45 July 5th, 1999 (yes, seconds since 1970 are valid as well) I<19970703 12:45> -- 12:45 July 3th, 1997 -(not quote standard, but I love this ...) - +(my favorite, and its even got an ISO number (8601)) =head1 AUTHOR Tobias Oetiker -