You should deploy your application as an exploded ear or war file and then update the configuration files in there. That avoids the issue of tmp going away when the server is restarted.
Thanks but that's not exactly what I need.
My problem is when the server shuts down it deletes the deployed web aplication, so when it is started again it redeployes the web app again. I only want the redeploy to occur once the war file has changes
I'm so sorry Peter, your answer right, is great. Thanks a lot.