developer-guidelines.sgml: Multiline output

Document the multiline output format properly.

Thanks to Jochen Bern for providing this patch.

1 files changed, 20 insertions, 8 deletions

diff --git a/doc/developer-guidelines.sgml b/doc/developer-guidelines.sgml
index 6b6f7357..599b2a16 100644
--- a/doc/developer-guidelines.sgml
+++ b/doc/developer-guidelines.sgml
@@ -83,10 +83,18 @@
                 STDOUT and not print to STDERR.</para>
 
                 <section><title>Print only one line of text</title>
-                <para>Nagios will only grab the first line of text from STDOUT
-                when it notifies contacts about potential problems. If you print
-                multiple lines, you're out of luck (though this will be a feature of 
-                Nagios 3). Remember, keep your output short and to the point.</para>
+                <para>Starting with version 3, Nagios will process plugins' multiline
+                output, which should be formatted as:</para>
+                <literallayout>
+                SERVICE STATUS: First line of output | First part of performance data
+                Any number of subsequent lines of output, but note that buffers
+                may have a limited size | Second part of performance data, which
+                may have continuation lines, too
+                </literallayout>
+                <para>Note, however, that the default configs still do not include
+                the output's continuation lines into the notifications sent when
+                Nagios notifies contacts about potential problems.
+                Thus, keep your output short and to the point.</para>
 
                 <para>Output should be in the format:</para>
                 <literallayout>
@@ -315,10 +323,14 @@
                 </section>
 
                 <section><title>Performance data</title>
-                <para>Performance data is defined by Nagios as "everything after the | of the plugin output" -
-                please refer to Nagios documentation for information on capturing this data to logfiles.
-                However, it is the responsibility of the plugin writer to ensure the 
-                performance data is in a "Nagios plugins" format.
+                <para>Nagios 3 and newer will concatenate the parts following a "|" in a) the first
+                line output by the plugin, and b) in the second to last line, into a string it
+                passes to whatever performance data processing it has configured. (Note that it
+                currently does not insert additional whitespace between both, so the plugin needs
+                to provide some to prevent the last pair of a) and the first of b) getting run
+                together.) Please refer to the Nagios documentation for information on how to
+                configure such processing. However, it is the responsibility of the plugin writer
+                to ensure the performance data is in a "Nagios plugins" format.
                 This is the expected format:</para>
 
                 <literallayout>