Log4J: Dynamically add hostname to filename

[ordawg]

I need to dynamically add the hostname to the filename that is
generated from my file appender.

I am not having any luck doing this and I have tried several variations
of the following:

<appender name="localapp"
class="org.apache.log4j.DailyRollingFileAppender">
<param name="File" value="../logs/$HOST-Application.log"/>
<param name="File" value="../logs/${env.host}-Application.log"/>
<param name="File" value="../logs/${env.HOST}-Application.log"/>
...

Any help would be greatly appreciated!