3.10.6 Troubleshooting a PC that Won t Boot

		console. This useful capability allows you to log in as root on a separate console to fix problems or change system configuration while leaving your user workspace unaffected.

		Pluggable authentication modules Linux also contains a highly configurable authentication mechanism called PAM. PAM is an Internet standard for customizing programs that require authentication so that the authentication mechanism can be changed without rewriting the program. For example, you normally log in to a system by typing in an account name and password. With PAM it is possible to substitute a face and speech recognition interface, or a fingerprint reader. That is not to say that PAM actually provides these advanced authentication mechanisms. It only provides the interface by which these mechanisms can be connected to programs requiring authentication. As biometrics research advances, Linux will be able to easily incorporate these new authentication methods. Already, alternate authentication systems, such as one-time passwords, have been deployed on Linux using PAM.

		Package management A constant problem faced in the administration of operating systems is the installation, removal, and upgrading of software packages. Several package management systems exist for Linux, but the one most widely adopted is RPM, the Red Hat Package Manager. Even though it was developed by Red Hat, it is not limited to Red Hat Linux systems, and several other distributions use the package format. RPM allows you to install a package and retain the ability to completely remove it from your system. It also allows you to query a file on your system to determine to which package it belongs. But most importantly, RPM allows an entire Linux system to be upgraded without having to start from scratch. RPM will resolve dependencies between multiple software packages and cleanly upgrade existing packages to newer versions.

		4.8 Installing an Initial System While a cookbook-style installation of a Linux distribution is beyond the scope of this book and is covered well in most distribution installation manuals, a few cluster-specific notes are in order.

		Linux installation procedures rely on the fact that most PC class machines will boot using the media in their floppy drive or CD-ROM drive as a source for the initial program to be run by the processor. If a suitable floppy or CD-ROM is installed, and the system is reset or power cycled, then the program on the floppy