What is yhe difference between "shell" and "kernel" in computer operating system ?  

In computer OS terms, a shell is a software program that interprets commands from the user so that the OS can understand them and perform the appropriate functions. It's the outermost layer of a program. Since the shell is only one layer above the OS, you can perform operations that are not always possible using the GUI. Whereas the kernel is the essential center of a computer OS, the core that provides basic services for all other parts of the OS. It is the part of the OS that loads first, and it remains in main memory. Typically, the kernel is responsible for memory management, process and task management, and disk management. The kernel in Windows doesn't manage the user's interface (more or less), whereas the shell does. When The kernel performs object management and other tasks, the shell manages how you open a folder for example.

Answered by A.R.Karthick at 3:05 PM on March 07, 2008

Well Gopal , the above two terms are major component of an operating system like Unix.

In fact the UNIX operating system is made up of three parts
1) kernel,
2) shell
3) programs.

The kernel of UNIX is the hub of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to system calls.

The shell acts as an interface between the user and the kernel. When a user logs in, the login program checks the username and password, and then starts another program called the shell.

The shell is a command line interpreter (CLI). It interprets the commands the user types in and arranges for them to be carried out.

The commands are themselves programs: when they terminate, the shell gives the user another prompt.

For more information , visit the source site :

http://www.earth.rochester.edu /ees254/unix_handout.html

Answered by alokgupta14 at 2:45 PM on March 07, 2008

In computing, a shell is a piece of software that provides an interface for users. Typically, the term refers to an operating system shell which provides access to the services of a kernel. However, the term is also applied very loosely to applications and may include any software that is "built around" a particular component, such as web browsers and email clients that are "shells" for HTML rendering engines. The name 'shell' originates from shells being an outer layer of interface between the user and the innards of the operating system (the kernel).Operating system shells generally fall into one of two categories: command line and graphical. Command line shells provide a command line interface (CLI) to the operating system, while graphical shells provide a graphical user interface (GUI). In either category the primary purpose of the shell is to invoke or "launch" another program, however, shells frequently have additional capabilities such as viewing the contents of directories.
The relative merits of CLI- and GUI-based shells are often debated. CLI proponents claim that certain operations can be performed much faster under CLI shells than under GUI shells (such as moving files, for example). However, GUI proponents advocate the comparative usability and simplicity of GUI shells. The best choice is often determined by the way in which a computer will be used. On a server mainly used for data transfers and processing with expert administration, a CLI is likely to be the best choice. On the other hand, a GUI would be more appropriate for a computer to be used for image or video editing and the development of the above data.

In computer science, the kernel is the central component of most computer operating systems (OS). Its responsibilities include managing the system's resources (the communication between hardware and software components).[1] As a basic component of an operating system, a kernel provides the lowest-level abstraction layer for the resources (especially memory, processors and I/O devices) that application software must control to perform its function. It typically makes these facilities available to application processes through inter-process communication mechanisms and system calls.
These tasks are done differently by different kernels, depending on their design and implementation. While monolithic kernels will try to achieve these goals by executing all the code in the same address space to increase the performance of the system, microkernels run most of their services in user space, aiming to improve maintainability and modularity of the codebase. A range of possibilities exists between these two extremes.Kernel development is considered one of the most complex and difficult tasks in programming.[9] Its central position in an operating system implies the necessity for good performance, which defines the kernel as a critical piece of software and makes its correct design and implementation difficult. For various reasons, a kernel might not even be able to use the abstraction mechanisms it provides to other software. Such reasons include memory management concerns (for example, a user-mode function might rely on memory being subject to demand paging, but as the kernel itself provides that facility it cannot use it, because then it might not remain in memory to provide that facility) and lack of reentrancy, thus making its development even more difficult for software engineers.

Answered by Kaushal at 1:54 PM on March 07, 2008