I have a web app running with logback logging file appender:

<appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
<!-- I'd prefer webapp relative path, but logback does not support that -->
<file>C:/webapp/log.lilith</file>
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<!-- daily rollover -->
<fileNamePattern>C:/webapp/oldLogs/log.%d

.lilith
</fileNamePattern>
<!-- keep 7 days' worth of history -->
<maxHistory>7</maxHistory>
</rollingPolicy>
<encoder class="de.huxhorn.lilith.logback.encoder.ClassicLilithEncoder">
<IncludeCallerData>true</IncludeCallerData>
</encoder>
</appender>

There is only one lilith file (over 1GB size) with all log entries in it from the time that file was created (no history limit, no rolling - oldLogs directory exists). Maybe this is Lilith bug, but previous versions of logback were leaving .tmp files as described in http://jira.qos.ch/browse/LOGBACK-173 so it looks logback was trying to do something.