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Introduction

IzPack installers use Java Logging for logging any information. If you want to customize it you should be familar with it, otherwise there is a good description of its principles in Oracle's Java Logging Overview.

Without any explicit specification on the command line or in the install.xml itself, an installer logs to the console at the given log level. For this purpose it associates a default Java ConsoleHandler combined with a built-in formatter not being that messy like the JRE's SimpleFormatter. The log level to limit the output to depends on whether you set IzPack to debug mode by adding the command line option -debug (or the -DDEBUG=true JVM option for IzPack versions < 5.1.0). If the installer runs in debug mode the Java Logging level for the root logger is set to FINE by default globally, by default it is INFO otherwise.

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Beyond the built-in logging mechanisms for console and file output there can be override the Java Logging configuration, handlers, formatters and their configuration at each desired Java package hierarchy you may add to an external configuration file, which can be passed as JVM command line option (standard approach of the LogManager API) or at compile time in the installer descriptor.

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