I recently upgraded my production instance to 11i.ATG_PF.H RUP 5 and replaced JInitiator with the Sun JRE Plugin. To be able to use Linux with the application’s applets, just perform the following steps:

1. Install Mozilla Firefox if you don’t already have it.
2. Download the supported JRE. In my case, it is 1.5.0_12. Because Oracle cannot keep up with new technology, I had to dig around in the Sun Java Archive to find it.
3. Copy the JRE bin file to where you want it installed. I copied mine to /opt.
4. Make the bin file executable:
   sudo chmod 744 jre-1_5_0_12-linux-i586.bin
5. Install the bin file:
   sudo jre-1_5_0_12-linux-i586.bin
6. Create a symlink to the JRE plugin:
   sudo ln -s /opt/jre1.5.0_12/plugin/i386/ns7/libjavaplugin_oji.so /usr/lib/firefox/plugins
   UPDATE: For Firefox 3:
   sudo ln -s /opt/jre1.5.0_12/plugin/i386/ns7/libjavaplugin_oji.so /usr/lib/firefox-addons/plugins
7. Startup Firefox, and give it a whirl.