I'm using Fedora Core 2 and I'm wondering if there's a way to automatically login into Runlevel 3. I've already added an option to get to RL3 in GRUB, which works and takes me to the console where it prompts for a username and password. Now I'd like to have it automatically log in using a user I've already created, then run a shell script. How can I do this? Thanks.

Install mingetty if you're not already using it and use it's 'autologin' option. Modify the tty1 entry in /etc/inittab accordingly. When it logs in it'll run ~/.bash_profile or whatever as normal but you don't need to be logged in just to run a shell script at start up. The only point of autologin is to reduce inconvenience for interactive users on single user machines. You don't need to use grub/kernel boot parameters just to get to RL3 at startup either - the correct way to do it is to modify the initdefault line in /etc/inittab

Thanks. I've done some additional looking and that's what I've found out. If I change the initdefault to RL3, can I still get to RL5 by running telinit 5? The reason I ask is that when I change runlevels with telinit I get an error messages saying that the "kernel doesn't support this mode". It usually boots fine anyway, but I'm curious what this error means. Thanks.

If telinit doesn't work properly with your kernel it's probably a Fedora problem. I've never come across that error before.