hello,
I am creating a customised version of slackware to work on my single board computer for a special device that will be like a talking file reader.
I want to have the system login by default as root without prompting the user and also use my customised menu driven program instead of the bash shell, or any shell for that matter.
can any one suggest how I can do that?

To get your root logged in try this.

edit /etc/rc.d/rc.local

and add the following lines:

echo "auto login for username"
cd /root
u - root

Method #2: Have a look at /etc/inittab. I'd also recommend reading the "man 5 inittab". You will need to spawn your menu program on a tty. I'm not sure of the best way for you to do that, but something as simple as this might work:

Not to be harsh but this is a poor idea. Root is not intended to run like a regular user, and instead should only be used in limited, infrequent situations (such as installing new packages or recompiling the kernel)

By running under root as a matter of routine, you are opening the door to all kinds of security risks, plus I would be willing to bet that it's only a matter of time before you accidentally trash your system - all it takes is one minor typo or one accidental mouse click and your system can be rendered unusable, with a full reinstall being your only option.

Again, I don't want to be harsh but you really don't want to do this. Regular user accounts exist for a reason - use them.

Yeah, I see no reason for this to be run as root.

I don't even see any reason for the system to forgo logins. You could spawn the menu program from inittab on tty1, and then leave tty2 for normal logins, or something along those lines.

hello,
I still can't figure out how I can change the system to use my own custom program instead of bash?
it is actually a menu system and I don't want bash to run because my users are not expected to type any thing.
the device I am developing is having 4 arrows, an escape key and enter key.

This is a bit dated, but it will give you an idea. It also describes how to start processes automatically on certain VC's.

"Make Your Virtual Console Log In Automatically"

http://linuxgazette.net/issue69/henderson.html

I would recommend that you make backups of any system files you change so you can go back to them just in case you mess up your system. Unless you really know what your doing, I suspect this will be a trial and error process. And has been mentioned already, accessing the system without user credentials verification will break your system security.