# NAME

rrdcgi - create web pages containing RRD graphs based on templates

PDF version.

# SYNOPSIS

#!/path/to/rrdcgi [--goodfor|-g seconds] [--filter] [--refresh|-r]

# DESCRIPTION

rrdcgi is a sort of very limited script interpreter. Its purpose is to run as a cgi-program and parse a web page template containing special <RRD:: tags. rrdcgi will interpret and act according to these tags. In the end it will printout a web page including the necessary CGI headers.

rrdcgi parses the contents of the template in 2 steps. In each step it looks only for a subset of tags. This allows to nest tags.

The argument parser uses the same semantics as you are used from your c shell.

--filter
  Assume that rrdcgi is being run as a filter and not as a cgi.

--refresh|-r
  If the --goodfor flag is specified, then --refresh will cause rrdcgi to output a Refresh header with the value of the --goodfor value.

## Pass 1

RRD::CV name
  Inserts the CGI variable of the given name.

RRD::CV::QUOTE name
  Inserts the CGI variable of the given name but quotes it, ready for use as an argument in another RRD:: tag. So even when there are spaces in the value of the CGI variable it will still be considered as one argument.

RRD::CV::PATH name
  Inserts the CGI variable of the given name, quotes it and makes sure the it starts neither with a '/' nor contains '..'. This is to make sure that no problematic pathnames can be introduced through the CGI interface.

RRD::GETENV variable
  Get the value of an environment variable.

       <RRD::GETENV REMOTE_USER>

  might give you the name of the remote user given you are using some sort of access control on the directory

## Pass 2

RRD::GOODFOR seconds
  Specify the number of seconds this page should remain valid. This will prompt the rrdcgi to output a Last-Modified, an Expire and if the number of seconds is negative a Refresh headers.

RRD::INCLUDE filename
  Include the contents of the given file into the page returned from the cgi

RRD::SETENV variable value
  If you want to present your graphs in another time zone than your own, you could use

       <RRD::SETENV TZ UTC>

  to make sure everything is presented in Universal Time. Note that the values permitted to TZ depend on your OS.

RRD::TIME::LAST rrd-file strftime-format
  This gets replaced by the last modification time of the selected RRD. The time is strftime-formated with the string specified in the second argument.

RRD::TIME::NOW strftime-format
  This gets replaced by the current time of day. The time is strftime-formated with the string specified in the argument.

## Pass 3

RRD::GRAPH rrdgraph arguments
  This tag creates the RRD graph defined in its argument and then gets replaced by an appropriate <IMG> tag referring to the graph. The --lazy option in RRD graph can be used to make sure that graphs are only regenerated when they are out of date. The arguments to the RRD::GRAPH tag work as described in the rrdgraph manual page.

  Use the --lazy option in your RRD::GRAPH tags, to reduce the load on your server. This option makes sure that graphs are only regenerated when the old ones are out of date.

  If you do not specify your own --imginfo format, the following will be used:

       <IMG SRC="%s" WIDTH="%lu" HEIGHT="%lu">

  Note that %s stands for the filename part of the graph generated, all directories given in the GIF file argument will get dropped.

RRD::PRINT number
  If the preceding RRD::GRAPH tag contained and PRINT arguments, then you can access their output with this tag. The number argument refers to the number of the PRINT argument. This first PRINT has number 0.

# EXAMPLE 1

The example below creates a web pages with a single RRD graph.

     #!/usr/local/bin/rrdcgi
     <HTML>
     <HEAD><TITLE>RRDCGI Demo</TITLE></HEAD>
     <BODY>
     <H1>RRDCGI Example Page</H1>
     <P>
     <RRD::GRAPH demo.gif --lazy --title="Temperatures"
              DEF:cel=demo.rrd:exhaust:AVERAGE
              LINE2:cel#00a000:"D. Celsius">

     </P>
     </BODY>
     </HTML>

# EXAMPLE 2

This script is slightly more elaborate, it allows you to run it from a form which sets RRD_NAME. RRD_NAME is then used to select which RRD you want to use a source for your graph.

     #!/usr/local/bin/rrdcgi
     <HTML>
     <HEAD><TITLE>RRDCGI Demo</TITLE></HEAD>
     <BODY>
     <H1>RRDCGI Example Page for <RRD::CV RRD_NAME></H1>
     <H2>Selection</H2>
     <FORM><INPUT NAME=RRD_NAME TYPE=RADIO VALUE=roomA> Room A,
           <INPUT NAME=RRD_NAME TYPE=RADIO VALUE=roomB> Room B.
           <INPUT TYPE=SUBMIT></FORM>
     <H2>Graph</H2>
     <P>
     <RRD::GRAPH <RRD::CV::PATH RRD_NAME>.gif --lazy
              --title "Temperatures for "<RRD::CV::QUOTE RRD_NAME>
              DEF:cel=<RRD::CV::PATH RRD_NAME>.rrd:exhaust:AVERAGE
              LINE2:cel#00a000:"D. Celsius">

     </P>
     </BODY>
     </HTML>

# EXAMPLE 3

This example shows how to handle the case where the RRD, graphs and cgi-bins are seperate directories

     #!/.../bin/rrdcgi
     <HTML>
     <HEAD><TITLE>RRDCGI Demo</TITLE></HEAD>
     <BODY>
     <H1>RRDCGI test Page</H1>
     <RRD::GRAPH
      /.../web/gifs/testhvt.gif
      --imginfo '<IMG SRC=/.../gifs/%s WIDTH=%lu HEIGHT=%lu >'
      --lazy --start -1d --end now
      DEF:http_src=/.../rrds/test.rrd:http_src:AVERAGE
      AREA:http_src#00ff00:http_src
     >
     </BODY>
     </HTML>

Note 1: Replace /.../ with the relevant directories

Note 2: The SRC=/.../gifs should be paths from the view of the webserver/browser

# AUTHOR

Tobias Oetiker <oetiker@ee.ethz.ch>