reset rrd_state for grapv in ruby bindings -- Sven Engelhardt

[rrdtool.git] / doc / rrdfetch.pod

diff --git a/doc/rrdfetch.pod b/doc/rrdfetch.pod
index a6382b9..0052aa6 100644 (file)
--- a/doc/rrdfetch.pod
+++ b/doc/rrdfetch.pod
@@ -4,10 +4,11 @@ rrdfetch - Fetch data from an RRD.
 
 =head1 SYNOPSIS
 
-B<rrdtool> B<fetch> I<filename> I<CF> 
-S<[B<--resolution>|B<-r> I<resolution>]> 
-S<[B<--start>|B<-s> I<start>]> 
-S<[B<--end>|B<-e> I<end>]> 
+B<rrdtool> B<fetch> I<filename> I<CF>
+S<[B<--resolution>|B<-r> I<resolution>]>
+S<[B<--start>|B<-s> I<start>]>
+S<[B<--end>|B<-e> I<end>]>
+S<[B<--daemon> I<address>]>
 
 =head1 DESCRIPTION
 
@@ -20,11 +21,11 @@ function.
 
 =over 8
 
-=item I<filename> 
+=item I<filename>
 
 the name of the B<RRD> you want to fetch the data from.
 
-=item I<CF> 
+=item I<CF>
 
 the consolidation function that is applied to the data you
 want to fetch (AVERAGE,MIN,MAX,LAST)
@@ -48,12 +49,21 @@ the end of the time series in seconds since epoch. See also AT-STYLE
 TIME SPECIFICATION section for a detailed explanation of how to
 specify the end time.
 
+=item B<--daemon> I<address>
+
+Address of the L<rrdcached> daemon. If specified, a C<flush> command is sent
+to the server before reading the RRD files. This allows B<rrdtool> to return
+fresh data even if the daemon is configured to cache values for a long time.
+For a list of accepted formats, see the B<-l> option in the L<rrdcached> manual.
+
+ rrdtool fetch --daemon unix:/var/run/rrdcached.sock /var/lib/rrd/foo.rrd AVERAGE
+
 =back
 
 =head2 RESOLUTION INTERVAL
 
-In order to get RRDtool to fetch anything other than the finest resolution RRA 
-B<both> the start and end time must be specified on boundaries that are 
+In order to get RRDtool to fetch anything other than the finest resolution RRA
+B<both> the start and end time must be specified on boundaries that are
 multiples of the desired resolution. Consider the following example:
 
  rrdtool create subdata.rrd -s 10 DS:ds0:GAUGE:300:0:U \
@@ -92,10 +102,10 @@ both start and end time are within the desired RRA
 
 =back
 
-So, if time now is called "t", do 
+So, if time now is called "t", do
 
  end time == int(t/900)*900,
- start time == end time - 1hour, 
+ start time == end time - 1hour,
  resolution == 900.
 
 Using the bash shell, this could look be:
@@ -103,7 +113,7 @@ Using the bash shell, this could look be:
  TIME=$(date +%s)
  RRDRES=900
  rrdtool fetch subdata.rrd AVERAGE -r $RRDRES \
-    -e $(echo $(($TIME/$RRDRES*$RRDRES))) -s e-1h
+    -e $(($TIME/$RRDRES*$RRDRES)) -s e-1h
 
 Or in Perl:
 
@@ -257,6 +267,22 @@ I<931225537> -- 18:45  July 5th, 1999
 I<19970703 12:45> -- 12:45  July 3th, 1997
 (my favorite, and its even got an ISO number (8601)).
 
+=head1 ENVIRONMENT VARIABLES
+
+The following environment variables may be used to change the behavior of
+C<rrdtoolE<nbsp>fetch>:
+
+=over 4
+
+=item B<RRDCACHED_ADDRESS>
+
+If this environment variable is set it will have the same effect as specifying
+the C<--daemon> option on the command line. If both are present, the command
+line argument takes precedence.
+
+=back
+
 =head1 AUTHOR
 
-Tobias Oetiker <oetiker@ee.ethz.ch>
+Tobias Oetiker E<lt>tobi@oetiker.chE<gt>
+