部署grails应用程序时stacktrace.log出现问题

log4j:ERROR setFile(null,true) call failed.
java.io.FileNotFoundException: stacktrace.log (Permission denied)
    at java.io.FileOutputStream.openAppend(Native Method)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:177)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:102)
    at org.apache.log4j.FileAppender.setFile(FileAppender.java:294)
    at org.apache.log4j.FileAppender.activateOptions(FileAppender.java:165)
    at org.apache.log4j.spi.OptionHandler$activateOptions.call(Unknown Source)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:120)
    at org.codehaus.groovy.grails.plugins.logging.Log4jConfig.createFullstackTraceAppender(Log4jConfig.groovy:177)
    at org.codehaus.groovy.grails.plugins.logging.Log4jConfig.this$2$createFullstackTraceAppender(Log4jConfig.groovy)
    at org.codehaus.groovy.grails.plugins.logging.Log4jConfig$this$2$createFullstackTraceAppender.callCurrent(Unknown Source)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:44)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:141)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:145)
    at org.codehaus.groovy.grails.plugins.logging.Log4jConfig.configure(Log4jConfig.groovy:145)
    at org.codehaus.groovy.grails.web.util.Log4jConfigListener.contextInitialized(Log4jConfigListener.java:62)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4135)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4630)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:445)
    at org.apache.catalina.core.StandardService.start(StandardService.java:519)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:581)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
May 25, 2011 11:16:54 PM org.apache.catalina.core.ApplicationContext log
INFO: Initializing Spring root WebApplicationContext

log4j = { 
    appenders {
        rollingFile name: \"stacktrace\", maxFileSize: 1024, file: \"/var/www/logs/myapp-stacktrace.log\"
     }
 }

-rwxr--r-- 1 tomcat6 root 0 May 24 18:38 myapp-stacktrace.log