log4c  1.2.4
Log4c : Logging for C Library
Summary Requirements Installation Configuration Customization Thanks Copyright


Log4c is a library of C for flexible logging to files, syslog and other destinations. It is modeled after the Log for Java library (http://jakarta.apache.org/log4j/), staying as close to their API as is reasonable. Here is a short introduction to Log4j which describes the API, and design rationale.

Mark Mendel started a parallel log4c projet with a different philosophy. The design is macro oriented, so much lighter and faster which perfect for kernel development.

Log4c is also available from SourceForge (http://www.sourceforge.net/projects/log4c/). This is work in progress.



log4c was successfully compiled and run on the following platforms:

log4c should compile and run on the following platforms:


The following software is needed to generate log4c:

For the moment, log4c uses specific GCC extensions, like attribute, so you will need GCC to compile it. This will probably change one day.


Building from source tarballs

on SourceForge:

The log4c package uses the GNU autotools compilation and installation framework. The following commands should build log4c on the supported platforms:

$ gzip -dc log4c-1.2.4.tar.gz | tar tvf -
$ cd log4c-1.2.4/
$ ./configure --prefix=/path/of/installation
$ make
$ make install

Checkout the INSTALL file for installation and the generated doxygen documentation for more information.


Configuration files

log4c searches the following files to load its configuration:

The environment variable LOG4C_RCPATH holds the prefix used for installation.

Configuration syntax

The log4crc configuration file uses an XML syntax. The root element is <log4c> and it can be used to control the configuration file version interface with the attribute "version". The following 4 elements are supported: <config>, <category>, <appender> and <layout>.

Here's the log4crc configuration file example:

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE log4c SYSTEM "">
<debug level="0"/>
<!-- root category ========================================= -->
<category name="root" priority="notice"/>
<!-- default appenders ===================================== -->
<appender name="stdout" type="stream" layout="basic"/>
<appender name="stderr" type="stream" layout="dated"/>
<appender name="syslog" type="syslog" layout="basic"/>
<!-- default layouts ======================================= -->
<layout name="basic" type="basic"/>
<layout name="dated" type="dated"/>

This initial version of the log4c configuration file syntax is quite different from log4j. XML seemed the best choice to keep the log4j configuration power in a C API.

Environment variables


This section will, one day, briefly describe how to define custom appenders and custom layouts. Be patient or checkout the source.


Mark Mendel for his work on a previous version of log4c.

This project would not have existed without Ceki Gulcu, the creator and maintainer of Log4j, nor without Bastiaan Bakker, who initiated me with Log4Cpp.

Many thanks to


All software in this package is Copyright (C) 2003-2004 Meiosys http://www.meiosys.com and Cedric Le Goater and is distributed under the LGPL License. See the COPYING file for full legal details.