Linux Directory Structure

Linux Features and Performance

Table 1.4: Linux Features and Performance Comparison
Characteristic	Linux	Windows NT	Solaris
Range of compatible hardware	Very wide	Modest	Narrow
Minimal hardware	386 PC	486 PC	Pentium
Representative cost of hardware	$200	$1300	$1600
Average downtime	Very low	As low as 30 min./week	Very low
Performance	High	Comparable to Linux	Half of Linux to same as Linux
Multi-processing capabilities	Excellent	Modest	Excellent
IP Security (IPSec)	Yes	Planned	1999
IPv6	Available	Privately demonstrated	Beta
Overall user satisfaction, per Datapro	Highest	Lowest	Medium
Source code readily available	Yes	No	No
Installed base	Millions	Millions	Hundreds of thousands

Captive user interface

A captive user interface or CUI is a style of interaction with an application that exists outside the scope of the highest level command interpreter present on the system.Once you invoke an application from command interpreter , it is not possible to communicate with the command interpreter until the application exists.

Ex :
$ mail command  for mailing
;;
$ exit
$ grep(searching) command
;;
$

Kernel functions

Kernel functions
Kernel is core of the Linux O.S.This interacts with the hardware.It  is loaded into the memory when a system is booted.
Functions
Managing the system resources
Allocating time for users and processes
Deciding process priorities and performing them

Structure of Linux System (Layered view of Linux O.S)

The X Window System

The X Window System

• Another important component of Linux is its graphical user interface, the X Window System. Unix was originally a mouseless, text-based system that used noisy teletype machines rather than modern CRT monitors. The Unix command interface is very sophisticated and, even today, some power users prefer it to a point-and-click graphical environment, using their CRT monitor as though it were a noiseless teletype. Consequently, some remain unaware that Unix long ago outgrew its text-based childhood, and now provides users a choice of graphical or command interfaces.

• X is a unique graphical user interface in two major respects. First, X integrates with a computer network, letting users access local and remote applications. For example, X lets you open a window that represents an application running on a remote server: the remote server does the heavy-duty computing; all your computer need do is pass the server your input and display the server's output.

• Second, X lets you configure its look and feel to an amazing degree. To do so, you run a special application - called a window manager - on top of X. A variety of window managers is available, including some that closely mimic the look and feel of Microsoft Windows.

Features of linux

•  The X Window system : X window system provides the foundation for the GUI available with Linux. (Windows feel and look).A user can  interact with computer through multiple windows on screen(Win look and feel).

• With the new version of linux, networking system has been made more reliable.Linux networking supports many valuable utilities that allow the user to access remote systems over a variety of networks.Can access files on disks mounted on other systems and also one user’s file accessible to other users.programs could be run on the machine and results will be displayed on another machine.

•  Linux is rich in its software development environment. Many computer languages have interpreters and compilers. Ex Ada,Pascal,C..Etc

•  Email programs common with linux are   mail,pine,mh,xmh,exmh,netscape mail and elm. These mail programs allow us to send and receive encoded binay messages.