RRDGRAPH(1) rrdtool RRDGRAPH(1)
rrdgraph - Round Robin Database tool grapher functions
rrdtool graph filename [option ...] [data definition ...] [data cal
culation ...] [variable definition ...] [graph element ...] [print
The graph function of RRDtool is used to present the data from an RRD
to a human viewer. Its main purpose is to create a nice graphical rep
resentation, but it can also generate a numerical report.
rrdtool graph needs data to work with, so you must use one or more data
definition statements to collect this data. You are not limited to one
database, its perfectly legal to collect data from two or more
databases (one per statement, though).
If you want to display averages, maxima, percentiles, etcetera it is
best to collect them now using the variable definition statement. Cur
rently 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 RRA is then consolidated so that there is
exactly one datapoint per pixel in the graph. If you do not take care
yourself, RRDtool will expand the range slightly 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 bytes per second, but want to
display bits per second. This is what the data calculation command is
designed for. After consolidating the data, a copy is made and this
copy is modified using a rather powerful RPN command set.
When you are done fetching and processing the data, it is time to graph
it (or print it). This ends the rrdtool graph sequence.
The name and path of the graph to generate. It is recommended to
end this in ".png", ".svg" or ".eps", but RRDtool does not enforce
filename can be "-" to send the image to "stdout". In this case,
no other output is generated.
[-s--start time] [-e--end time] [-S--step seconds]
The start and end of the time series you would like to display, and
which RRA the data should come from. Defaults are: 1 day ago until
now, with the best possible resolution. Start and end can be speci
fied in several formats, see AT-STYLE TIME SPECIFICATION and rrd
graph_examples. By default, rrdtool graph calculates the width of
one pixel in the time domain and tries to get data from an RRA with
that resolution. With the step option you can alter this
behaviour. If you want rrdtool graph to get data at a one-hour
resolution from the RRD, set step to 3600. Note: a step smaller
than one pixel will silently be ignored.
[-t--title string] [-v--vertical-label string]
A horizontal string at the top of the graph and/or a vertically
placed string at the left hand side of the graph.
[-w--width pixels] [-h--height pixels] [-j--only-graph]
The width and height of the canvas (the part of the graph with the
actual data and such). This defaults to 400 pixels by 100 pixels.
If you specify the --only-graph option and set the height < 32 pix
els 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.
[-u--upper-limit value] [-l--lower-limit value] [-r--rigid]
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 lower-limit to upper-limit. Autoscaling will still
permit those boundaries to be stretched unless the rigid option is
Sometimes the default algorithm for selecting the y-axis scale is
not satisfactory. Normally the scale is selected from a predefined
set of ranges and this fails miserably when you need to graph some
thing like "260 + 0.001 * sin(x)". This option calculates the mini
mum and maximum y-axis from the actual minimum and maximum data
values. Our example would display slightly less than "260-0.001" to
slightly more than "260+0.001" (this feature was contributed by
Where "--alt-autoscale" will modify both the absolute maximum AND
minimum values, this option will only affect the maximum value. The
minimum 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.
In order to avoid anti-aliasing effects gridlines are placed on
integer pixel values. This is by default done by extending the
scale so that gridlines happens to be spaced using an integer num
ber of pixels and also start on an integer pixel value. This might
extend the scale too much for some logarithmic scales and for lin
ear scales where --alt-autoscale is needed. Using --no-gridfit
disables modification of the scale.
The x-axis label is quite complex to configure. If you dont
have very special needs it is probably best to rely on the
autoconfiguration to get this right. You can specify the string
"none" to suppress the grid and labels altogether.
The grid is defined by specifying a certain amount of time in
the ?TM positions. You can choose from "SECOND", "MINUTE",
"HOUR", "DAY", "WEEK", "MONTH" or "YEAR". Then you define how
many of these should pass between each line or label. This
pair (?TM:?ST) needs to be specified for the base grid (G??),
the major grid (M??) and the labels (L??). For the labels you
also must define a precision in LPR and a strftime format
string in LFM. LPR defines where each label will be placed. If
it is zero, the label will be placed right under the corre
sponding line (useful for hours, dates etcetera). If you spec
ify a number of seconds here the label is centered on this
interval (useful for Monday, January etcetera).
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.
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
[-y--y-grid grid step:label factor]
Y-axis grid lines appear at each grid step interval. Labels
are placed every label factor lines. You can specify "-y none"
to suppress the grid and labels altogether. The default for
this option is to automatically select sensible values.
Place the Y grid dynamically based on the graphs 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 met
ric. That is the grid lines are placed every 1, 2, 5 or 10
units. This parameter will also ensure that you get enough dec
imals displayed even if your graph goes from 69.998 to 70.001.
(contributed by Sasha Mikheev).
Logarithmic y-axis scaling.
This sets the 10**exponent scaling of the y-axis values. Nor
mally, 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 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.
This option is very effective at confusing the heck out of the
default rrdtool autoscaler and grid painter. If rrdtool detects
that it is not successful in labeling the graph under the given
circumstances, it will switch to the more robust --alt-y-grid
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.
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.
Only generate the graph if the current graph is out of date or not
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 function is supplied with the
parameters filename, xsize and ysize. In order to generate an IMG
tag suitable for including the graph into a web page, the command
line would look like this:
Override the default colors for the standard elements of the graph.
The COLORTAG is one of "BACK" background, "CANVAS" for the back
ground of the actual graph, "SHADEA" for the left and top border,
"SHADEB" for the right and bottom border, "GRID", "MGRID" for the
major grid, "FONT" for the color of the font, "AXIS" for the axis
of the graph, "FRAME" for the line around the color spots and
finally "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: "--color ARROW#00FF00"
Zoom the graphics by the given amount. The factor must be > 0
This lets you customize which font to use for the various text ele
ments on the RRD graphs. "DEFAULT" sets the default value for all
elements, "TITLE" for the title, "AXIS" for the axis labels, "UNIT"
for the vertical unit label, "LEGEND" for the graph legend.
Use Times for the title: "--font TITLE:13:/usr/lib/fonts/times.ttf"
If you do not give a font string you can modify just the sice of
the default font: "--font TITLE:13:".
If you specify the size 0 then you can modify just the font without
touching the size. This is especially usefull for altering the
default font without resetting the default fontsizes: "--font
RRDtool comes with a preset default font. You can set the environ
ment variable "RRD_DEFAULT_FONT" if you want to change this.
Truetype fonts are only supported for PNG output. See below.
This lets you customize the strength of the font smoothing, or dis
able it entirely using mono. By default, normal font smoothing is
This specifies the largest font size which will be rendered
bitmapped, that is, without any font smoothing. By default, no text
is rendered bitmapped.
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.
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, Hel
vetica-BoldOblique, Helvetica-Oblique, Helvetica, Symbol,
Times-Bold, Times-BoldItalic, Times-Italic, Times-Roman, and ZapfD
If images are interlaced they become visible on browsers more
Suppress generation of the legend; only render the graph.
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).
By default the tab-width is 40 pixels, use this option to change
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 mea
surement, 1 kb/s is 1000 b/s.
Adds the given string as a watermark, horizontally centred, at the
bottom of the graph.
Data and variables
You need at least one DEF statement to generate anything. The other
statements are useful but optional. See rrdgraph_data and rrd
graph_rpn for the exact format.
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 rrdgraph_graph
for the exact format.
rrdgraph gives an overview of how rrdtool graph works. rrdgraph_data
describes DEF,CDEF and VDEF in detail. rrdgraph_rpn describes the RPN
language used in the ?DEF statements. rrdgraph_graph page describes
all of the graph and print functions.
Make sure to read rrdgraph_examples for tips&tricks.
Program by Tobias Oetiker
This manual page by Alex van den Bogaerdt
1.2.15 2006-07-14 RRDGRAPH(1)