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+++ b/doc/rrdfetch.html
<body style="background-color: white">
-<p><a name="__index__"></a></p>
+
<!-- INDEX BEGIN -->
+<div name="index">
+<p><a name="__index__"></a></p>
<!--
<ul>
<ul>
<li><a href="#resolution_interval">RESOLUTION INTERVAL</a></li>
- <li><a href="#atstyle_time_specification">AT-STYLE TIME SPECIFICATION</a></li>
+ <li><a href="#at_style_time_specification">AT-STYLE TIME SPECIFICATION</a></li>
<li><a href="#time_reference_specification">TIME REFERENCE SPECIFICATION</a></li>
<li><a href="#time_offset_specification">TIME OFFSET SPECIFICATION</a></li>
<li><a href="#time_specification_examples">TIME SPECIFICATION EXAMPLES</a></li>
</ul>
+ <li><a href="#environment_variables">ENVIRONMENT VARIABLES</a></li>
<li><a href="#author">AUTHOR</a></li>
</ul>
+
-->
+
+
+</div>
<!-- INDEX END -->
<p>
<p><strong>rrdtool</strong> <strong>fetch</strong> <em>filename</em> <em>CF</em>
[<strong>--resolution</strong>|<strong>-r</strong> <em>resolution</em>]
[<strong>--start</strong>|<strong>-s</strong> <em>start</em>]
-[<strong>--end</strong>|<strong>-e</strong> <em>end</em>]</p>
+[<strong>--end</strong>|<strong>-e</strong> <em>end</em>]
+[<strong>--daemon</strong> <em>address</em>]</p>
<p>
</p>
<hr />
function to get data from <strong>RRD</strong>s. <strong>fetch</strong> will analyze the <strong>RRD</strong>
and try to retrieve the data in the resolution requested.
The data fetched is printed to stdout. <em>*UNKNOWN*</em> data is often
-represented by the string ``NaN'' depending on your OS's printf
+represented by the string "NaN" depending on your OS's printf
function.</p>
<dl>
-<dt><strong><a name="item_filename"><em>filename</em></a></strong></dt>
+<dt><strong><a name="filename" class="item"><em>filename</em></a></strong></dt>
<dd>
<p>the name of the <strong>RRD</strong> you want to fetch the data from.</p>
</dd>
-<dt><strong><a name="item_cf"><em>CF</em></a></strong></dt>
+<dt><strong><a name="cf" class="item"><em>CF</em></a></strong></dt>
<dd>
<p>the consolidation function that is applied to the data you
want to fetch (AVERAGE,MIN,MAX,LAST)</p>
</dd>
-<dt><strong><a name="item_resolution"><strong>--resolution</strong>|<strong>-r</strong> <em>resolution</em> (default is the highest resolution)</a></strong></dt>
+<dt><strong><a name="resolution" class="item"><strong>--resolution</strong>|<strong>-r</strong> <em>resolution</em> (default is the highest resolution)</a></strong></dt>
<dd>
<p>the interval you want the values to have (seconds per
value). <strong>rrdfetch</strong> will try to match your request, but it will return
data even if no absolute match is possible. <strong>NB.</strong> See note below.</p>
</dd>
-<dt><strong><a name="item_start"><strong>--start</strong>|<strong>-s</strong> <em>start</em> (default end-1day)</a></strong></dt>
+<dt><strong><a name="start" class="item"><strong>--start</strong>|<strong>-s</strong> <em>start</em> (default end-1day)</a></strong></dt>
<dd>
<p>start of the time series. A time in seconds since epoch (1970-01-01)
one day worth of data will be fetched. See also AT-STYLE TIME SPECIFICATION
section for a detailed explanation on ways to specify the start time.</p>
</dd>
-<dt><strong><a name="item_end"><strong>--end</strong>|<strong>-e</strong> <em>end</em> (default now)</a></strong></dt>
+<dt><strong><a name="end" class="item"><strong>--end</strong>|<strong>-e</strong> <em>end</em> (default now)</a></strong></dt>
<dd>
<p>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.</p>
</dd>
+<dt><strong><a name="daemon_address" class="item"><strong>--daemon</strong> <em>address</em></a></strong></dt>
+
+<dd>
+<p>Address of the <a href="././rrdcached.html">the rrdcached manpage</a> daemon. If specified, a <code>flush</code> command is sent
+to the server before reading the RRD files. This allows <strong>rrdtool</strong> 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 <strong>-l</strong> option in the <a href="././rrdcached.html">the rrdcached manpage</a> manual.</p>
+<pre>
+ rrdtool fetch --daemon unix:/var/run/rrdcached.sock /var/lib/rrd/foo.rrd AVERAGE</pre>
+</dd>
</dl>
<p>
</p>
<p>both start and end time are within the desired RRA</p>
</li>
</ol>
-<p>So, if time now is called ``t'', do</p>
+<p>So, if time now is called "t", do</p>
<pre>
end time == int(t/900)*900,
start time == end time - 1hour,
-r $rrdres -e @{[int($ctime/$rrdres)*$rrdres]} -s e-1h"'</pre>
<p>
</p>
-<h2><a name="atstyle_time_specification">AT-STYLE TIME SPECIFICATION</a></h2>
+<h2><a name="at_style_time_specification">AT-STYLE TIME SPECIFICATION</a></h2>
<p>Apart from the traditional <em>Seconds since epoch</em>, RRDtool does also
understand at-style time specification. The specification is called
-``at-style'' after the Unix command <code>at(1)</code> that has moderately complex
+"at-style" after the Unix command <code>at(1)</code> that has moderately complex
ways to specify time to run your job at a certain date and time. The
at-style specification consists of two parts: the <strong>TIME REFERENCE</strong>
specification and the <strong>TIME OFFSET</strong> specification.</p>
@@ -171,11 +189,16 @@ full date in several numerical formats, including <strong>MM/DD/[YY]YY</strong>,
single-number date is interpreted as MMDD[YY]YY.</p>
<p><em>NOTE2</em>: if you specify the <em>day</em> in this way, the <em>time-of-day</em> is
REQUIRED as well.</p>
-<p>Finally, you can use the words <strong>now</strong>, <strong>start</strong>, or <strong>end</strong> as your time
+<p>Finally, you can use the words <strong>now</strong>, <strong>start</strong>, <strong>end</strong> or <strong>epoch</strong> as your time
reference. <strong>Now</strong> refers to the current moment (and is also the default
time reference). <strong>Start</strong> (<strong>end</strong>) can be used to specify a time
relative to the start (end) time for those tools that use these
-categories (<strong>rrdfetch</strong>, <a href="././rrdgraph.html">the rrdgraph manpage</a>).</p>
+categories (<strong>rrdfetch</strong>, <a href="././rrdgraph.html">the rrdgraph manpage</a>) and <strong>epoch</strong> indicates the
+*IX epoch (*IX timestamp 0 = 1970-01-01 00:00:00 UTC). <strong>epoch</strong> 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. <strong>epoch</strong>+19711205s unambiguously
+denotes timestamp 19711205 and not 1971-12-05 00:00:00 UTC.</p>
<p>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
words <strong>now</strong>, <strong>start</strong>, <strong>end</strong> can be abbreviated as <strong>n</strong>, <strong>s</strong>, <strong>e</strong>.</p>
<p>
</p>
<hr />
+<h1><a name="environment_variables">ENVIRONMENT VARIABLES</a></h1>
+<p>The following environment variables may be used to change the behavior of
+<code>rrdtoolfetch</code>:</p>
+<dl>
+<dt><strong><a name="rrdcached_address" class="item"><strong>RRDCACHED_ADDRESS</strong></a></strong></dt>
+
+<dd>
+<p>If this environment variable is set it will have the same effect as specifying
+the <code>--daemon</code> option on the command line. If both are present, the command
+line argument takes precedence.</p>
+</dd>
+</dl>
+<p>
+</p>
+<hr />
<h1><a name="author">AUTHOR</a></h1>
<p>Tobias Oetiker <<a href="mailto:tobi@oetiker.ch">tobi@oetiker.ch</a>></p>