1. What are multiuser systems? Why are they successful? 2. What is the Free Software Foundation/GNU? What is Linux? Which parts of the Linux operating system did each provide? Who else has helped build and refine this operating system? 3. What is a shell? How does it work with the kernel and with the user?

Explanation:

1)A multi user system is a computer operating system which allows multiple users to access the single system the single system with one operating system on it.it is generally used on large mainframe computer.

They are successful because of the powerful, efficient, stable and secure operating systems like LINUX. it has a capability of providing each user the same data ensuring total privacy from each user even while accessed by 100's of users simultaneously.

2)“Free software” means software that respects users' freedom and community. Roughly, it means that the users have the freedom to run, copy, distribute, study, change and improve the software. Thus, “free software” is a matter of liberty, not price. GNU is an operating system which is 100% free software. It was launched in 1983 by Richard Stallman (rms) and has been developed by many people working together for the sake of freedom of all software users to control their computing. Technically, GNU is generally like Unix. But unlike Unix, GNU gives its users freedom.

Linux is the best known and most used open source operating system,it is the software that sits underneath all of the other software on a computer,it receives request from those pros and relay these request to the computer hardware.

Linux systems tend to fall into several classes, each of which draw from a different set of components.

Each kind of system includes the Linux kernel and the tools necessary to support at least one Linux file system. Each kind of system includes other run time libraries, utilities and applications. The run time support and applications can be general purpose or they can be tailored to the system’s use.

1)Desktop systems are probably what most people think of when they answer this question. They are normally based on distributions and there are hundreds of distributions. It is normally possible to tailor a distribution but typically they have

a)POSIX compliant shared libraries and commands, often from the Free Software Foundation

b)A Windowing system, commonly X Windows, which is most often from X.Org

c)A Window manager system such as Gnome or KDE

d)A tailored set of applications depending on the user’s need. Development tools such as compilers and header files are included in developer distributions but not in others, for example.

2)Server systems are desktop systems from which the windowing system and window manager are typically removed, but otherwise are often from the same distributions as desktops, only configured differently at install time.

3)Purpose built embedded systems use something like Busy box rather than the FSF GNU tools, often omit the windowing system and window manager and often have very limited sets of utilities and applications. Routers often fall in this category

4)Custom run time systems are designed to replace the POSIX compliant run time system with one that is purpose built. They tend to have custom GUIS and are designed so that the user doesn’t normally access the system management tools. Roku’s streaming box and Android are well known examples.

3) A shell is a software interface that's often a command line interface that enables the user to interact with the computer. Some examples of shells are MS-DOS Shell (command.com), csh, ksh, PowerShell, sh, and tcsh.

It works with the kernel and the user by allowing the user to interface with the kernel from the command line.