X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=doc%2Frrdfetch.pod;h=29f91bc4d873291ca240a3a3f3f6bd06c2ea5607;hb=825f213df6f751b4e48fe7dcd64feeb27b10cc59;hp=7ebd9d603bb84dc0705f0c2a621fb6343b03be48;hpb=cb092381724e4ba8a1f18712fefc541a3d370f99;p=rrdtool.git

diff --git a/doc/rrdfetch.pod b/doc/rrdfetch.pod
index 7ebd9d6..29f91bc 100644
--- a/doc/rrdfetch.pod
+++ b/doc/rrdfetch.pod
@@ -8,6 +8,7 @@ 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
 
@@ -48,6 +49,22 @@ 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
+
+Please note that due to thread-safety reasons, the time specified with B<-s>
+and B<-e> cannot use the complex forms described in
+L<"AT-STYLE TIME SPECIFICATION">. The only accepted arguments are "simple
+integers". Positive values are interpreted as seconds since epoch, negative
+values (and zero) are interpreted as relative to I<now>. So "1272535035" refers
+to "09:57:15 (UCT), April 29th 2010" and "-3600" means "one hour ago".
+
 =back
 
 =head2 RESOLUTION INTERVAL
@@ -103,7 +120,7 @@ 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:
 
@@ -148,11 +165,16 @@ single-number date is interpreted as MMDD[YY]YY.
 I<NOTE2>: if you specify the I<day> in this way, the I<time-of-day> is
 REQUIRED as well.
 
-Finally, you can use the words B<now>, B<start>, or B<end> as your time
+Finally, you can use the words B<now>, B<start>, B<end> or B<epoch> as your time
 reference. B<Now> refers to the current moment (and is also the default
 time reference). B<Start> (B<end>) can be used to specify a time
 relative to the start (end) time for those tools that use these
-categories (B<rrdfetch>, L<rrdgraph>).
+categories (B<rrdfetch>, L<rrdgraph>) and B<epoch> indicates the 
+*IX epoch (*IX timestamp 0 = 1970-01-01 00:00:00 UTC). B<epoch> is
+useful to disambiguate between a timestamp value and some forms
+of abbreviated date/time specifications, because it allows to use 
+time offset specifications using units, eg. B<epoch>+19711205s unambiguously
+denotes timestamp 19711205 and not 1971-12-05 00:00:00 UTC.
 
 Month and day of the week names can be used in their naturally
 abbreviated form (e.g., Dec for December, Sun for Sunday, etc.). The
@@ -257,6 +279,22 @@ 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>
+