How can I get log4j to delete old rotating log files?

Question

How can I get log4j to delete old rotating log files? I know I can set up automated jobs (cron for UNIX and scheduled task for Windows), but I want it cross platform, and I want it in our application's log configuration as a part of our application, rather than in separate code outside in OS specific scripting languages. Our application is not written in OS scripting languages, and I don't want to do this part of it in them.

Answer 1

RollingFileAppender does this. You just need to set maxBackupIndex to the highest value for the backup file.

Answer 2

Logs rotate for a reason, so that you only keep so many log files around. In log4j.xml you can add this to your node:

<param name="MaxBackupIndex" value="20"/>

The value tells log4j.xml to only keep 20 rotated log files around. You can limit this to 5 if you want or even 1. If your application isn't logging that much data, and you have 20 log files spanning the last 8 months, but you only need a weeks worth of logs, then I think you need to tweak your log4j.xml "MaxBackupIndex" and "MaxFileSize" params.

Alternatively, if you are using a properties file (instead of the xml) and wish to save 15 files (for example)

log4j.appender.[appenderName].MaxBackupIndex = 15

Answer 3

There is no default value to control deleting old log files created by DailyRollingFileAppender. But you can write your own custom Appender that deletes old log files in much the same way as setting maxBackupIndex does for RollingFileAppender.

Simple instructions found here

From 1:

If you are trying to use the Apache Log4J DailyRollingFileAppender for a daily log file, you may need to want to specify the maximum number of files which should be kept. Just like rolling RollingFileAppender supports maxBackupIndex. But the current version of Log4j (Apache log4j 1.2.16) does not provide any mechanism to delete old log files if you are using DailyRollingFileAppender. I tried to make small modifications in the original version of DailyRollingFileAppender to add maxBackupIndex property. So, it would be possible to clean up old log files which may not be required for future usage.