X-Git-Url: https://git.octo.it/?p=rrdtool.git;a=blobdiff_plain;f=doc%2Frrdgraph.pod;h=57359ac66972b176f1f253067e8711a376030f22;hp=bd0d0d46265b281206803a8771e3a2f5550f593f;hb=07de871981951c5ff711ae94ce2c69f0423c3987;hpb=1ed31d581dfed23377a61d4df88bb9c2b9b2c94b

diff --git a/doc/rrdgraph.pod b/doc/rrdgraph.pod
index bd0d0d4..57359ac 100644
--- a/doc/rrdgraph.pod
+++ b/doc/rrdgraph.pod
@@ -4,7 +4,7 @@ rrdgraph - Round Robin Database tool grapher functions
 
 =head1 SYNOPSIS
 
-B<rrdtool graph> I<filename>
+B<rrdtool graph|graphv> I<filename>
 [I<L<option|rrdgraph/OPTIONS>> ...]
 [I<L<data definition|rrdgraph_data/DEF>> ...]
 [I<L<data calculation|rrdgraph_data/CDEF>> ...]
@@ -16,70 +16,73 @@ B<rrdtool graph> I<filename>
 
 The B<graph> function of B<RRDtool> is used to present the
 data from an B<RRD> to a human viewer.  Its main purpose is to
-create a nice graphical representation but it can also generate
+create a nice graphical representation, but it can also generate
 a numerical report.
 
 =head1 OVERVIEW
 
-B<rrdtool graph> needs data to work with, use one or more
+B<rrdtool graph> needs data to work with, so you must use one or more
 B<L<data definition|rrdgraph_data/DEF>> statements to collect this
 data.  You are not limited to one database, it's perfectly legal to
-collect data from two or more databases (one per statement though).
+collect data from two or more databases (one per statement, though).
 
-If you want to display averages, maxima, percentiles etcetera
+If you want to display averages, maxima, percentiles, etcetera
 it is best to collect them now using the
 B<L<variable definition|rrdgraph_data/VDEF>> statement.
-Currently this makes no difference but in a future version
+Currently this makes no difference, but in a future version
 of rrdtool you may want to collect these values before consolidation.
 
 The data fetched from the B<RRA> is then B<consolidated> so that
 there is exactly one datapoint per pixel in the graph. If you do
 not take care yourself, B<RRDtool> will expand the range slightly
-if necessary (in that case the first and/or last pixel may very
-well become unknown!).
-
-Sometimes data is not exactly as you would like to display it. For
-instance, you might be collecting B<bytes> per second but want to
-display B<bits> per second. This is where the
-B<L<data calculation|rrdgraph_data/CDEF>> command is designed for.
-After B<consolidating> the data, a copy is made and this copy is
-modified using a rather flexible B<L<RPN|rrdgraph_rpn/>> command
-set.
+if necessary. Note, in that case the first and/or last pixel may very
+well become unknown!
+
+Sometimes data is not exactly in the format you would like to display
+it. For instance, you might be collecting B<bytes> per second, but
+want to display B<bits> per second. This is what the B<L<data
+calculation|rrdgraph_data/CDEF>> command is designed for. After
+B<consolidating> the data, a copy is made and this copy is modified
+using a rather powerful B<L<RPN|rrdgraph_rpn>> command set.
 
 When you are done fetching and processing the data, it is time to
 graph it (or print it).  This ends the B<rrdtool graph> sequence.
 
+Use B<graphv> instead of B<graph> to get detailed information about the
+graph geometry and data once it is drawn. See the bottom of the document for
+more information.
+
 =head1 OPTIONS
 
-=over 4
 
-=item filename
+
+=head2 I<filename>
 
 The name and path of the graph to generate. It is recommended to
-end this in C<.png>, C<.svg> or C<.eps> but B<RRDtool> does not enforce this.
+end this in C<.png>, C<.svg> or C<.eps>, but B<RRDtool> does not enforce this.
 
 I<filename> can be 'C<->' to send the image to C<stdout>. In
-that case, no other output is generated.  
+this case, no other output is generated.
 
-=item Time range
+=head2 Time range
 
 [B<-s>|B<--start> I<time>]
 [B<-e>|B<--end> I<time>]
 [B<-S>|B<--step> I<seconds>]
 
-The start and end of what you would like to display, and which
+The start and end of the time series you would like to display, and which
 B<RRA> the data should come from.  Defaults are: 1 day ago until
-now, with the best possible resolution. B<Start> and B<end> can 
+now, with the best possible resolution. B<Start> and B<end> can
 be specified in several formats, see
-L<AT-STYLE TIME SPECIFICATION|rrdfetch/> and L<rrdgraph_examples>.
+L<AT-STYLE TIME SPECIFICATION|rrdfetch> and L<rrdgraph_examples>.
 By default, B<rrdtool graph> calculates the width of one pixel in
 the time domain and tries to get data from an B<RRA> with that
 resolution.  With the B<step> option you can alter this behaviour.
 If you want B<rrdtool graph> to get data at a one-hour resolution
-from the B<RRD>, set B<step> to 3600.  Note: a step smaller than
+from the B<RRD>, set B<step> to 3'600. Note: a step smaller than
 one pixel will silently be ignored.
 
-=item Labels
+=head2 Labels
 
 [B<-t>|B<--title> I<string>]
 [B<-v>|B<--vertical-label> I<string>]
@@ -87,41 +90,56 @@ one pixel will silently be ignored.
 A horizontal string at the top of the graph and/or a vertically
 placed string at the left hand side of the graph.
 
-=item Size
+
+=head2 Size
 
 [B<-w>|B<--width> I<pixels>]
 [B<-h>|B<--height> I<pixels>]
 [B<-j>|B<--only-graph>]
+[B<-D>|B<--full-size-mode>]
+
+By default, the width and height of the B<canvas> (the part with
+the actual data and such). This defaults to 400 pixels by 100 pixels.
 
-The width and height of the B<canvas> (the part of the graph with
-the actual lines and such). Defaults are 400 pixels by 100 pixels.
+If you specify the B<--full-size-mode> option, the width and height
+specify the final dimensions of the output image and the canvas
+is automatically resized to fit.
 
 If you specify the B<--only-graph> option and set the height E<lt> 32
-pixels you will get a tiny graph image to use as an icon in a potential
-overview. All labeling will be stripped off the graph.
+pixels you will get a tiny graph image (thumbnail) to use as an icon
+for use in an overview, for example. All labeling will be stripped off
+the graph.
 
-=item Limits
+=head2 Limits
 
 [B<-u>|B<--upper-limit> I<value>]
 [B<-l>|B<--lower-limit> I<value>]
 [B<-r>|B<--rigid>]
 
-By default the graph will be autoscaling so that it displays the
-portion of the y-axis that is actually used. You can change this
-behaviour by setting the limits.  The displayed y-axis will show
-at least from B<lower-limit> to B<upper-limit>.  Autoscaling will
-still permit those boundaries to be stretched unless the B<rigid>
-option is set.
+By default the graph will be autoscaling so that it will adjust the
+y-axis to the range of the data. You can change this behaviour by
+explicitly setting the limits. The displayed y-axis will then range at
+least from B<lower-limit> to B<upper-limit>. Autoscaling will still
+permit those boundaries to be stretched unless the B<rigid> option is
+set.
 
 [B<-A>|B<--alt-autoscale>]
 
 Sometimes the default algorithm for selecting the y-axis scale is not
-performing very well.  Normally the scale is selected from a predefined
+satisfactory. Normally the scale is selected from a predefined
 set of ranges and this fails miserably when you need to graph something
 like C<260 + 0.001 * sin(x)>. This option calculates the minimum and
-maximum y-axis from the actual minimum and maximum values. Our example
+maximum y-axis from the actual minimum and maximum data values. Our example
 would display slightly less than C<260-0.001> to slightly more than
-C<260+0.001> (Contributed by Sasha Mikheev).
+C<260+0.001> (this feature was contributed by Sasha Mikheev).
+
+[B<-J>|B<--alt-autoscale-min>]
+
+Where C<--alt-autoscale> will modify both the absolute maximum AND minimum
+values, this option will only affect the minimum value. The maximum
+value, if not defined on the command line, will be 0. This option can
+be useful when graphing router traffic when the WAN line uses compression,
+and thus the throughput may be higher than the WAN line speed.
 
 [B<-M>|B<--alt-autoscale-max>]
 
@@ -133,27 +151,22 @@ and thus the throughput may be higher than the WAN line speed.
 
 [B<-N>|B<--no-gridfit>]
 
-To avoid anti-aliasing effects gridlines are placed on 
-integer pixel values. This is by default done by extending 
-the scale so gridlines happens to be spaced using an 
-integer number of pixels, and starts on integer pixel value.
-This might extend the scale too much for some logarithmic scales
-and for linear scales where B<--alt-autoscale> is needed.
-Using B<--no-gridfit> disables modification of the scale.
+In order to avoid anti-aliasing blurring effects rrdtool snaps
+points to device resolution pixels, this results in a crisper
+appearance. If this is not to your liking, you can use this switch
+to turn this behaviour off.
 
-=item Grid
+Gridfitting is turned off for PDF, EPS, SVG output by default.
 
-=over 4
-
-=item X-Axis
+=head2 X-Axis
 
 [B<-x>|B<--x-grid> I<GTM>B<:>I<GST>B<:>I<MTM>B<:>I<MST>B<:>I<LTM>B<:>I<LST>B<:>I<LPR>B<:>I<LFM>]
 
 [B<-x>|B<--x-grid> B<none>]
 
-The x-axis label is quite complex to configure, if you don't have
+The x-axis label is quite complex to configure. If you don't have
 very special needs it is probably best to rely on the autoconfiguration
-to get this right.  You can specify the string C<none> to skip the grid
+to get this right. You can specify the string C<none> to suppress the grid
 and labels altogether.
 
 The grid is defined by specifying a certain amount of time in the I<?TM>
@@ -161,26 +174,26 @@ positions. You can choose from C<SECOND>, C<MINUTE>, C<HOUR>, C<DAY>,
 C<WEEK>, C<MONTH> or C<YEAR>. Then you define how many of these should
 pass between each line or label.  This pair (I<?TM:?ST>) needs to be
 specified for the base grid (I<G??>), the major grid (I<M??>) and the
-labels (I<L??>). For the labels you also need to define a precision
+labels (I<L??>). For the labels you also must define a precision
 in I<LPR> and a I<strftime> format string in I<LFM>.  I<LPR> defines
 where each label will be placed. If it is zero, the label will be
 placed right under the corresponding line (useful for hours, dates
 etcetera).  If you specify a number of seconds here the label is
-centered in this interval (useful for Monday, January etcetera).
+centered on this interval (useful for Monday, January etcetera).
 
  --x-grid MINUTE:10:HOUR:1:HOUR:4:0:%X
 
-This places grid lines every 10 minutes, major grid lines every hour
+This places grid lines every 10 minutes, major grid lines every hour,
 and labels every 4 hours. The labels are placed under the major grid
 lines as they specify exactly that time.
 
- --x-grid HOUR:8:DAY:1:DAY:1:0:%A
+ --x-grid HOUR:8:DAY:1:DAY:1:86400:%A
 
 This places grid lines every 8 hours, major grid lines and labels
 each day. The labels are placed exactly between two major grid lines
 as they specify the complete day and not just midnight.
 
-=item Y-Axis
+=head2 Y-Axis
 
 [B<-y>|B<--y-grid> I<grid step>B<:>I<label factor>]
 
@@ -188,15 +201,21 @@ as they specify the complete day and not just midnight.
 
 Y-axis grid lines appear at each I<grid step> interval.  Labels are
 placed every I<label factor> lines.  You can specify C<-y none> to
-skip the grid and labels altogether.  The default for this option is
+suppress the grid and labels altogether.  The default for this option is
 to automatically select sensible values.
 
+If you have set --y-grid to 'none' not only the labels get suppressed, also
+the space reserved for the labels is removed. You can still add space
+manually if you use the --units-length command to explicitly reserve space.
+
 [B<-Y>|B<--alt-y-grid>]
 
-Place Y grid dynamically based on graph Y range. Algorithm ensures
-that you always have grid, that there are enough but not too many
-grid lines and the grid is metric. That is grid lines are placed
-every 1, 2, 5 or 10 units.  (contributed by Sasha Mikheev)
+Place the Y grid dynamically based on the graph's Y range. The algorithm
+ensures that you always have a grid, that there are enough but not too many
+grid lines, and that the grid is metric. That is the grid lines are placed
+every 1, 2, 5 or 10 units. This parameter will also ensure that you get
+enough decimals displayed even if your graph goes from 69.998 to 70.001. 
+(contributed by Sasha Mikheev).
 
 [B<-o>|B<--logarithmic>]
 
@@ -204,12 +223,12 @@ Logarithmic y-axis scaling.
 
 [B<-X>|B<--units-exponent> I<value>]
 
-This sets the 10**exponent scaling of the y-axis values.  Normally
-values will be scaled to the appropriate units (k, M, etc.).  However
+This sets the 10**exponent scaling of the y-axis values. Normally,
+values will be scaled to the appropriate units (k, M, etc.).  However,
 you may wish to display units always in k (Kilo, 10e3) even if the data
-is in the M (Mega, 10e6) range for instance.  Value should be an
-integer which is a multiple of 3 between -18 and 18 inclusive.  It is
-the exponent on the units you which to use.  For example, use 3 to
+is in the M (Mega, 10e6) range, for instance. Value should be an
+integer which is a multiple of 3 between -18 and 18 inclusively.  It is
+the exponent on the units you wish to use. For example, use 3 to
 display the y-axis values in k (Kilo, 10e3, thousands), use -6 to
 display the y-axis values in u (Micro, 10e-6, millionths).  Use a value
 of 0 to prevent any scaling of the y-axis values.
@@ -221,23 +240,80 @@ to the more robust B<--alt-y-grid> mode.
 
 [B<-L>|B<--units-length> I<value>]
 
-How many digits should rrdtool assume the y-axis labels to be ? You may have to use this option
-to make enough space once you start fideling with the y-axis labeling.
+How many digits should rrdtool assume the y-axis labels to be? You
+may have to use this option to make enough space once you start
+fiddling with the y-axis labeling.
 
-=back
+[B<--units=si>]
+
+With this option y-axis values on logarithmic graphs will be scaled to 
+the appropriate units (k, M, etc.) instead of using exponential notation.
+Note that for linear graphs, SI notation is used by default.
 
-=item Miscellaneous
+=head2 Right Y Axis
+
+[B<--right-axis> I<scale>B<:>I<shift>]
+[B<--right-axis-label> I<label>]
+
+A second axis will be drawn to the right of the graph. It is tied to the
+left axis via the scale and shift parameters. You can also define a label
+for the right axis.
+
+[B<--right-axis-format> I<format-string>]
+
+By default the format of the axis lables gets determined automatically. If
+you want todo this your self, use this option with the same %lf arguments
+you know from the PRING and GPRINT commands.
+
+=head2 Legend
+
+[B<-g>|B<--no-legend>]
+
+Suppress generation of the legend; only render the graph.
+
+[B<-F>|B<--force-rules-legend>]
+
+Force the generation of HRULE and VRULE legends even if those HRULE or
+VRULE will not be drawn because out of graph boundaries (mimics
+behaviour of pre 1.0.42 versions).
+
+[B<--legend-position>=(north|south|west|east)]
+
+Place the legend at the given side of the graph. The default is south.
+In west or east position it is necessary to add line breaks manually.
+
+[B<--legend-direction>=(topdown|bottomup)]
+
+Place the legend items in the given vertical order. The default is topdown.
+Using bottomup the legend items appear in the same vertical order as a
+stack of lines or areas.
+
+=head2 Miscellaneous
 
 [B<-z>|B<--lazy>]
 
-Only generate the graph, if the current graph is out of date or not
-existent.
+Only generate the graph if the current graph is out of date or not existent.
+Note, that all the calculations will happen regardless so that the output of
+PRINT and graphv will be complete regardless. Note that the behaviour of
+lazy in this regard has seen several changes over time. The only thing you
+can realy rely on before rrdtool 1.3.7 is that lazy will not generate the
+graph when it is already there and up to date, and also that it will output
+the size of the graph. 
+
+[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 the graph to contain
+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 graph [...] --daemon unix:/var/run/rrdcached.sock [...]
 
 [B<-f>|B<--imginfo> I<printfstr>]
 
 After the image has been created, the graph function uses printf
 together with this format string to create output similar to the PRINT
-function, only that the printf is supplied with the parameters
+function, only that the printf function is supplied with the parameters
 I<filename>, I<xsize> and I<ysize>. In order to generate an B<IMG> tag
 suitable for including the graph into a web page, the command line
 would look like this:
@@ -250,51 +326,123 @@ Override the default colors for the standard elements of the graph. The
 I<COLORTAG> is one of C<BACK> background, C<CANVAS> for the background of
 the actual graph, C<SHADEA> for the left and top border, C<SHADEB> for the
 right and bottom border, C<GRID>, C<MGRID> for the major grid, C<FONT> for
-the color of the font, C<AXIS> for the axis of the graph and finaly C<ARROW>
-for the arrow head pointing to the future. Each color is composed out of
-three hexadecimal numbers specifying its color component (00 is off, FF is
-maximum) of red, green and blue. Optionally you may add another hexadecimal
-number specifying the transparency (FF is solid). You may set this option
-several times to alter multiple defaults.
+the color of the font, C<AXIS> for the axis of the graph, C<FRAME> for the
+line around the color spots, and finally C<ARROW> for the arrow head pointing
+up and forward. Each color is composed out of three hexadecimal numbers
+specifying its rgb color component (00 is off, FF is maximum) of red, green
+and blue. Optionally you may add another hexadecimal number specifying the
+transparency (FF is solid). You may set this option several times to alter
+multiple defaults.
 
-A green arrow is made by: C<--color ARROW:00FF00>
+A green arrow is made by: C<--color ARROW#00FF00>
 
 [B<--zoom> I<factor>]
 
-Zoom the graphics by the given amount ... The factor must be E<gt> 0
+Zoom the graphics by the given amount. The factor must be E<gt> 0
+
+[B<-n>|B<--font> I<FONTTAG>B<:>I<size>B<:>[I<font>]]
+
+This lets you customize which font to use for the various text elements on
+the RRD graphs. C<DEFAULT> sets the default value for all elements, C<TITLE>
+for the title, C<AXIS> for the axis labels, C<UNIT> for the vertical unit
+label, C<LEGEND> for the graph legend, C<WATERMARK> for the watermark on the
+edge of the graph.
 
-[B<-n>|B<--font> I<FONTTAG>B<:>I<size>B<:>I<font>]
+Use Times for the title: C<--font TITLE:13:Times>
 
-Lets you customize which font to use for the various text elements on the
-RRD graphs. C<DEFAULT> sets the default value for all elements C<TITLE>,
-C<AXIS> for the axis labels, C<UNIT> for the vertical unit label, C<LEGEND>
-for the graph legend.
+Note that you need to quote the argument to B<--font> if the font-name
+contains whitespace:
+--font "TITLE:13:Some Font"
 
-Use Times for the title: C<--font TITLE:13:/usr/lib/fonts/times.ttf>
+If you do not give a font string you can modify just the size of the default font:
+C<--font TITLE:13:>.
+
+If you specify the size 0 then you can modify just the font without touching
+the size. This is especially useful for altering the default font without
+resetting the default fontsizes: C<--font DEFAULT:0:Courier>.
 
 RRDtool comes with a preset default font. You can set the environment
 variable C<RRD_DEFAULT_FONT> if you want to change this.
 
-Truetype fonts are only supported for PNG output. See below.
+RRDtool uses Pango for its font handling. This means you can to use
+the full Pango syntax when selecting your font:
 
-[B<-a>|B<--imgformat> B<PNG>|B<SVG>|B<EPS>|B<PDF>]
+The font name has the form "[I<FAMILY-LIST>] [I<STYLE-OPTIONS>] [I<SIZE>]",
+where I<FAMILY-LIST> is a comma separated list of families optionally
+terminated by a comma, I<STYLE_OPTIONS> is a whitespace separated list of
+words where each WORD describes one of style, variant, weight, stretch, or
+gravity, and I<SIZE> is a decimal number (size in points) or optionally
+followed by the unit modifier "px" for absolute size. Any one of the options
+may be absent.
 
-Image format for the generated graph. For the vector formats you can choose among the standard Postscript fonts
-Courier-Bold, Courier-BoldOblique, Courier-Oblique, Courier, Helvetica-Bold,
-Helvetica-BoldOblique, Helvetica-Oblique, Helvetica, Symbol, Times-Bold, Times-BoldItalic,
-Times-Italic, Times-Roman, ZapfDingbats 
+[B<-R>|B<--font-render-mode> {B<normal>,B<light>,B<mono>}]
 
-[B<-i>|B<--interlaced>]
+There are 3 font render modes:
 
-If images are interlaced they become visible on browsers more quickly.
+B<normal>: Full Hinting and Antialiasing (default)
 
-[B<-g>|B<--no-legend>]
+B<light>: Slight Hinting and Antialiasing
 
-Suppress generation of legend; only render the graph.
+B<mono>: Full Hinting and NO Antialiasing
 
-[B<-F>|B<--force-rules-legend>]
 
-Force the generation of HRULE and VRULE legend even if those HRULE or VRULE will not be drawn because out of graph boundaries (mimics behaviour of pre 1.0.42 versions).
+[B<-B>|B<--font-smoothing-threshold> I<size>]
+
+(this gets ignored in 1.3 for now!)
+
+This specifies the largest font size which will be rendered
+bitmapped, that is, without any font smoothing. By default,
+no text is rendered bitmapped.
+
+[B<-P>|B<--pango-markup>]
+
+All text in rrdtool is rendered using Pango. With the B<--pango-markup> option, all
+text will be processed by pango markup. This allows to embed some simple html
+like markup tags using 
+
+ <span key="value">text</span>
+
+Apart from the verbose syntax, there are also the following short tags available.
+
+ b     Bold
+ big   Makes font relatively larger, equivalent to <span size="larger">
+ i     Italic
+ s     Strikethrough
+ sub   Subscript
+ sup   Superscript
+ small Makes font relatively smaller, equivalent to <span size="smaller">
+ tt    Monospace font
+ u     Underline 
+
+More details on L<http://developer.gnome.org/doc/API/2.0/pango/PangoMarkupFormat.html>.
+
+[B<-G>|B<--graph-render-mode> {B<normal>,B<mono>}]
+
+There are 2 render modes:
+
+B<normal>: Graphs are fully Antialiased (default)
+
+B<mono>: No Antialiasing
+
+[B<-E>|B<--slope-mode>]
+
+RRDtool graphs are composed of stair case curves by default. This is in line with
+the way RRDtool calculates its data. Some people favor a more 'organic' look
+for their graphs even though it is not all that true.
+
+[B<-a>|B<--imgformat> B<PNG>|B<SVG>|B<EPS>|B<PDF>]
+
+Image format for the generated graph. For the vector formats you can
+choose among the standard Postscript fonts Courier-Bold,
+Courier-BoldOblique, Courier-Oblique, Courier, Helvetica-Bold,
+Helvetica-BoldOblique, Helvetica-Oblique, Helvetica, Symbol,
+Times-Bold, Times-BoldItalic, Times-Italic, Times-Roman, and ZapfDingbats.
+
+[B<-i>|B<--interlaced>]
+
+(this gets ignored in 1.3 for now!)
+
+If images are interlaced they become visible on browsers more quickly.
 
 [B<-T>|B<--tabwidth> I<value>]
 
@@ -306,7 +454,12 @@ If you are graphing memory (and NOT network traffic) this switch
 should be set to 1024 so that one Kb is 1024 byte. For traffic
 measurement, 1 kb/s is 1000 b/s.
 
-=item Data and variables
+[B<-W>|B<--watermark> I<string>]
+
+Adds the given string as a watermark, horizontally centered, at the bottom 
+of the graph.
+
+=head2 Data and variables
 
 B<DEF:>I<vname>B<=>I<rrdfile>B<:>I<ds-name>B<:>I<CF>[B<:step=>I<step>][B<:start=>I<time>][B<:end=>I<time>]
 
@@ -316,28 +469,72 @@ B<VDEF:>I<vname>B<=>I<RPN expression>
 
 You need at least one B<DEF> statement to generate anything. The
 other statements are useful but optional.
-See L<rrdgraph_data> and L<rrdgraph_rpn> for exact format.
+See L<rrdgraph_data> and L<rrdgraph_rpn> for the exact format.
 
-=item Graph and print elements
+NOTE: B<Graph and print elements>
 
 You need at least one graph element to generate an image and/or
 at least one print statement to generate a report.
-See L<rrdgraph_graph> for exact format.
+See L<rrdgraph_graph> for the exact format.
+
+=head2 graphv
+
+Calling rrdtool with the graphv option will return information in the
+rrdtool info format. On the command line this means that all output will be
+in key=value format. When used from the Perl and Ruby bindings a hash
+pointer will be returned from the call.
+
+When the filename '-' is given, the contents of the graph itself will also
+be returned through this interface (hash key 'image'). On the command line
+the output will look like this:
+
+ print[0] = "0.020833"
+ print[1] = "0.0440833"
+ graph_left = 51
+ graph_top = 22
+ graph_width = 400
+ graph_height = 100
+ graph_start = 1232908800
+ graph_end = 1232914200
+ image_width = 481
+ image_height = 154
+ value_min = 0.0000000000e+00
+ value_max = 4.0000000000e-02
+ image = BLOB_SIZE:8196
+ [... 8196 bytes of image data ...]
+
+There is more information returned than in the standard interface.
+Especially the 'graph_*' keys are new. They help applications that want to
+know what is where on the graph.
+
+=head1 ENVIRONMENT VARIABLES
+
+The following environment variables may be used to change the behavior of
+C<rrdtoolE<nbsp>graph>:
+
+=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 SEE ALSO
 
 L<rrdgraph> gives an overview of how B<rrdtool graph> works.
-L<rrdgraph_data> describes B<DEF>,B<CDEF> and B<VDEF> in detail,
-L<rrdgraph_rpn> describes the B<RPN> language used in the B<?DEF> statements,
+L<rrdgraph_data> describes B<DEF>,B<CDEF> and B<VDEF> in detail.
+L<rrdgraph_rpn> describes the B<RPN> language used in the B<?DEF> statements.
 L<rrdgraph_graph> page describes all of the graph and print functions.
 
 Make sure to read L<rrdgraph_examples> for tipsE<amp>tricks.
 
 =head1 AUTHOR
 
-Program by Tobias Oetiker E<lt>oetiker@ee.ethz.chE<gt>
+Program by Tobias Oetiker E<lt>tobi@oetiker.chE<gt>
 
-This manual page by Alex van den Bogaerdt E<lt>alex@ergens.op.het.netE<gt>
+This manual page by Alex van den Bogaerdt E<lt>alex@vandenbogaerdt.nlE<gt>
+with corrections and/or additions by several people