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From Robert Kleemann <rob...@kleemann.org>
Subject Re: how to search and replace message text in outgoing log messages?
Date Thu, 14 Feb 2013 23:17:20 GMT
I ended up writing a class that extends PatternLayout and it seems to
work.  Here it is in case anyone else needs it.

package org.scharp.util;

import org.apache.log4j.PatternLayout;
import org.apache.log4j.spi.LoggingEvent;

 * <p>
 * This class is a drop in replacement for a log4j PatternLayout
class. It can be referenced via a log4j properties file
 * just like an ordinary PatternLayout.
 * <p>
 * The only difference between this class and the parent class is that
newlines are replace by a replacement string.
 * This allows downstream log viewers to receive a single log message
that contains multiple lines and correctly
 * reconstruct it as a single, viewable message.
 * @author kleemann
public class NewLinePatternLayout extends PatternLayout {

    public static final String NL_REPLACEMENT = "!!!NL!!!";

    public NewLinePatternLayout() {

    public NewLinePatternLayout(String pattern) {

     * If we don't render the throwable then it will be rendered by
the Appender which will likely display it on
     * separate lines.
    public boolean ignoresThrowable() {
        return false;

    public String format(LoggingEvent event) {
        String original = super.format(event);
        StringBuilder sb = new StringBuilder(original.replace("\n",

        String[] s = event.getThrowableStrRep();
        if (s != null) {
            for (int i = 0; i < s.length; i++) {

        return sb.toString();


On Sat, Jan 19, 2013 at 9:35 AM, Robert Kleemann <robert@kleemann.org> wrote:
> I have have a need to replace newlines with a different character
> sequence on messages going to my SyslogAppender.  I have quite a few
> programs sending log info to syslog so I was hoping that I could do
> this completely within the xml configuration file but I can't seem to
> find a way to make this happen.  Is this correct?  Is there a way to
> perform a search and replace within the message field via the xml
> config file?
> The fallback is to write some code to do the configuration.  I'm
> thinking that the best way to do this in 1.2.17 is to write a class
> that extends PatternLayout and then reference that from the xml file.
> Is this the cleanest way to implement this?
> thanks!
> Robert.

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