Q: On Unix (Linux), login failed because of the file write permission.

A: If you installed Bugzero with the root user and run the application
   server (on which Bugzero is deployed) as a non-root user, then, you
   will have a problem to write the log file and/or compile the jsp code.

   You need either chown (to the Tomcat user), or chmod (so that the Tomcat
   user can write), or run the app sever as root.