How to configure jetty to put its logs into an external file?

Manual says that I have to put slf4j into the lib directory.

What I did was:

download slf4j and put slf4j-log4j12-1.7.3.jar into $JETTY_HOME$/lib .
download log4j and put log4j-1.2.17.jar into $JETTY_HOME$/lib
create a log4j configuration file. it's available from below:

<appender name="fileAppender" class="org.apache.log4j.RollingFileAppender">
  <param name="Threshold" value="DEBUG" />    
  <param name="File" value="c:/app/jetty/logs/server.log" />
  <layout class="org.apache.log4j.PatternLayout">   <param name="ConversionPattern" value="%d  %-5p  [%c{1}] %m %n" />
  </layout>
</appender>
<root>
  <priority value="debug" />
  <appender-ref ref="fileAppender" />
</root>

commented line

"#org.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.StdErrLog" in $JETTY_HOME$/resources/jetty-logging.properties

Although I did everything what's described above, I am not able to see any logs in the target destinations. All log entries are still available from the console

Updated Instructions (June 2016)

For Jetty 9+, you'll be using a split ${jetty.home} and ${jetty.base} directory.

Note: do not edit/modify/delete/add/remove any content in ${jetty.home}. All of your configuration will reside in ${jetty.base} from now on.

Instructions as command line:

$ mkdir /path/to/mybase
$ cd /path/to/mybase

# Prepare a basic jetty.base directory
$ java -jar /path/to/jetty-dist/start.jar --add-to-start=http,deploy,resources,ext
INFO: ext             initialised in ${jetty.base}/start.ini
INFO: resources       initialised in ${jetty.base}/start.ini
INFO: server          initialised (transitively) in ${jetty.base}/start.ini
INFO: http            initialised in ${jetty.base}/start.ini
INFO: deploy          initialised in ${jetty.base}/start.ini
MKDIR: ${jetty.base}/lib
MKDIR: ${jetty.base}/lib/ext
MKDIR: ${jetty.base}/resources
MKDIR: ${jetty.base}/webapps
INFO: Base directory was modified

# Download the required jar files
$ cd /path/to/mybase/lib/ext
$ curl -O http://central.maven.org/maven2/org/slf4j/slf4j-api/1.7.21/slf4j-api-1.7.21.jar
$ curl -O http://central.maven.org/maven2/org/slf4j/slf4j-log4j12/1.7.21/slf4j-log4j12-1.7.21.jar
$ curl -O http://central.maven.org/maven2/log4j/log4j/1.2.17/log4j-1.2.17.jar

# Prepare the Jetty side logging to use slf4j
$ cd /path/to/mybase/resources
$ echo "org.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.Slf4jLog" > jetty-logging.properties

# Grab a copy of a log4j.xml to initialize things
$ cd /path/to/mybase/resources
$ curl -o log4j.xml https://gist.githubusercontent.com/joakime/13e31db59b83079be3fdc1a877de7060/raw/5c275a2a2f29445d6cdde7fcae3820da99e7234b/log4j.xml

# Start Jetty
$ cd /path/to/mybase
$ java -jar /path/to/jetty-dist/start.jar

Note: do not enable the logging module as that is strictly for Jetty's StdErrLog implementation. That logging module will capture any System.err and System.out and redirect it to a rolling log file. This capture and redirect will be in direct conflict with your log4j ConsoleAppender!

Original Instructions - Only valid on Jetty 8 (now EOL) and older

Follow these steps:

create a logging directory in $JETTY_HOME/lib: $JETTY_HOME/lib/logging (this is just best practice)
put log4j, slf4j-log4j and slf4j-api in that directory: e.g.: log4j-1.2.16.jar slf4j-api-1.6.1.jar slf4j-log4j12-1.6.1.jar
make sure to have that new directory in jetty's classpath by adding "logging" in your $JETTY_HOME/start.ini OPTIONS line: e.g.: OPTIONS=Server,websocket,resources,ext,jsp,jdbc,logging
place your log4j.properties in $JETTY_HOME/resources directory
start jetty