External log4j.xml file

Question

I am trying to run a jar with the log4j.xml file on the file system outside the jar like so:

java -jar MyJarName.jar -cp=/opt/companyName/pathToJar/ log4j.co         


        

Answer 1

The simplest path configuration for ``log4j2is using thestatic blocksettinglog4j.configurationFile`:

public class MyClass {

    static {
        System.setProperty("log4j.configurationFile", "./config/log4j2.xml");
    }

    protected final transient Logger logger =  LogManager.getLogger(IDOLTracker.class);

    public static void main(String[] args) {
         logger.info("");
    }
}

Then the structure could be as:

ProgramFolder
|---- /config/log4j2.xml
|---- MyClass.jar

When you run your jar, it will look outside the jar for the xml file.

Answer 2

"-jar" only uses the classpath inside the executable jar, and -cp is ignored. Adding "." to the classpath in the executable jar should allow log4j.xml to be fount.

Answer 3

For log4j2, use configurationFile option:

java -Dlog4j.configurationFile=/path/to/log4j2.xml -jar ...

http://logging.apache.org/log4j/2.0/manual/configuration.html

Answer 4

I had problems using log4j with Sun's JDK and automatic configuration.

You can use this:

String filename = System.getProperty("log4j.configuration");
DOMConfigurator(filename);

before using Logger.

Answer 5

java -cp "path/to/your/log4jxml:path/to/yourjar.jar" your.package.MainClass

The log4j.xml in directory "path/to/your/log4jxml" will overwrite the log4j.xml file in "path/to/yourjar.jar".

Please refer to Setting multiple jars in java classpath.

Answer 6

When using the -jar switch to launch an executable jar file, the classpath is obtained from the jar file's manifest. The -cp switch, if given, is ignored.

Jeff Storey's answer is going to be the easiest solution. Alternatively, you could add a Class-Path attribute to the jar file's manifest.

EDIT Try enabling log4j debugging, and making the path to log4j.xml a fully-qualified URL. For example:

java -Dlog4j.debug -Dlog4j.configuration=file:/path/to/log4j.xml -jar ...