X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=doc%2Frrdfetch.pod;h=29f91bc4d873291ca240a3a3f3f6bd06c2ea5607;hb=9d7aa8ddae065b774fe4eb1df76a3242b9db2d53;hp=d187b69e9db48b0152bfa519d71dabc187002b66;hpb=ac630adec930653637199258efd99024d49325c7;p=rrdtool.git

diff --git a/doc/rrdfetch.pod b/doc/rrdfetch.pod
index d187b69..29f91bc 100644
--- a/doc/rrdfetch.pod
+++ b/doc/rrdfetch.pod
@@ -53,13 +53,18 @@ specify the end time.
 
 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. To
-specify a UNIX domain socket use the prefix C<unix:>, see example below. Other
-addresses are interpreted as normal network addresses, i.E<nbsp>e. IPv4 or IPv6
-addresses in most cases.
+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
@@ -160,11 +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