We have multiple databases and I don't know what the URL is to launch OEM. What is the easiest way of discovering this? Is there a Launcher tool that would detect all available OEMs and allow me to launch them?
If you have a lot of db's and use DBConsole it would be more efficient to use Grid/Cloud control to have a central montoring tool.
To find the console port to use you have to look in every Oracle home in the install directory in the file portlist.ini.
$ORACLE_HOME/install/portlist.ini The console port is the number in the line that contains "Console HTTP Port".
To start the console enter in your browser: http://[hostname]:<port number>/em after you have started Database Console of course.