Technology And Computer|

Anyone who is uses computers today will be familiar with Windows and Linux as operating systems. Some prefer Windows because it is extremely easy to use – both hardware and software – and some prefer Linux because it is much more flexible is use; above all it is open source ware and hence it is free. Those who enjoy Linux are totally baffled as to why people would want to pay for something that you can get absolutely free.

Actually there is a simple and logical answer to this question. When the Windows was launched some 20 plus years ago, it caught like wild fire because it was all of a sudden so easy to use and so convenient to install. The best things that it maintained a constant identity – as the product of Windows, while on the other hand Linux went along under many names, such as Knoppix, Mandrake, SuSe, Windows, and so on. With each name (different companies) Linux as an operating system had slight variations. Hence, it was bothersome for people to keep track, and sometime use Linux due to this aspect.

Then comes the inherent difference between these operation systems. Technically speaking, you will find the GUI is optional in the Linux operations system while it is part and parcel of the Windows. The separation of the GUI directly affects the reliability and speed – not to mention efficiency – of a server and hence here Linux scores over the Windows.

Another major difference is in the way these operating systems handle their command prompts. While Windows uses similar command interpreters for its Windows 9x versions, the NT series have a different style but common to each other. Linux on the other hand, being a UNIX version has the capability of handling multiple command interpreters, which can be a boon, though it mostly favors Bourne Again Shell (BASH). The other interpreters that you will find in Linux are C Shell, ash, Korn shell and so on.

The best and most highlighted difference is the price tag attached to the operating systems. Windows is an expensive to say the least, operating system which comes with a copyrighted license, while Linux is free for all, easily downloadable anytime you want it. The downside here is that Linux has instruction which will tell you what to do – which may be why people are indeed reluctant to move away from Windows; though there are a few low cost Linux versions which come with automation and manuals.

Another plus in favor of Linux is the lack of any security requirement. The viruses, spy wares, malawares and what not you have it are all a product of Microsoft, for Windows. Hence, while you have to use high security firewalls with Windows, you are free from any such headaches with Linux.

Lastly, you have the difference of availability of software. The majority of the software that you find on the market are for Windows and they will not run on Linux unless Windows is somewhere configured as a subsystem which actually goes against the reason of using Linux in the first place.

Hence, till a suitable interface is found where Linux can be compatible with Windows without using Windows itself, have a few clear-cut instructions for first time users and sufficient information on its technicalities, people will prefer Windows to Linux, even if they have to pay to use it.

A shell is the command interpreter program that serves as an interface between some users and the operating system itself. We say some users because most users rely on the graphical user interface. The Windows shell is the DOS command line interface accessed by clicking on Run and then entering the cmd command. The Windows graphical user interface is Explorer. This article describes the Damn Small Linux shell interface and several utilities, useful programs that may be launched from the shell. A subsequent article will describe the corresponding graphical user interface.

Why would anyone want to bother with a shell when the prettier, easier-to-learn and easier-to-use graphical interface is available? The answer is: It depends who you are and what you want to do. For system administrators or their associates it’s often much less cumbersome to use the shell rather than the graphical user interface. While Damn Small Linux commands may be quite arcane, they can be very powerful. And efficient. The Linux tools for performing administrative and other technical tasks admittedly take time to learn and master. But it does the job and does it well. In all fairness, many Windows systems administrators often apply command-line utilities. But they don’t have a powerful shell to help them do their work.

Historically Unix used the Bourne shell, the C shell based on the C programming language, and the Korn shell. Linux’s most widely used shell is Bash, also spelled BASH, the (Bourne-Again Shell). Damn Small Linux offers many shells but most people go with Bash both to communicate interactively with the operating system and to write programs known as shell scripts. If you program in Linux no matter which programming language you use you should learn some Bash specifics.

Utilities enable you to handle some very sophisticated processing. You can think of them as commands or as prewritten programs. Unix-Linux people often send the output of one command or utility to another command or utility for further processing. For example, the ps command displays active processes. It tends to generate voluminous output, especially in a busy system. Let’s say that you are interested only in the processes associated with a given terminal. You send (the technical term is pipe, expressed by the | character) the output of the ps command to the grep utility which looks for patterns within the input. You code a single line, multipart command to obtain the list of processes associated with that particular terminal. Unix and Linux are well known for elegant solutions. In contrast the Windows solution to this information need is much more clumsy.

The grep utility has many other uses including validating e-mail addresses. Let’s say that your web site asks potential subscribers to furnish their e-mail accounts when signing up for a newsletter. A sophisticated but relatively short statement coded in grep could validate e-mail accounts.

Other Damn Small Linux text processing utilities include the related egrep and fgrep commands, mawk a pattern scanning and text processing language, sed an editor that handles large files, and diff a utility that compares files. DSL provides utilities that compress and archive files, and a wide range of other utilities. If you need them, these Linux utilities can be quite useful and time-saving.

Our next subject is Linux programming support.

Unix and Linux are both POSIX compliant operating systems. POSIX defined a standard interface to the low-level operating system which greatly reduces the amount of work required to produce UNIX and Linux software.

Unix and Linux software development

The standard user command line and scripting interface was based on the Korn shell. Other user-level programs, services and utilities include awk, echo, ed, and hundreds of others. Required program-level services include basic I/O (file, terminal, and network) services. POSIX also defines a standard threading library API which is supported by most modern operating systems.

Currently POSIX documentation is divided in three parts:

POSIX Kernel APIs

POSIX Commands and Utilities

POSIX Conformance Testing

Linux Development requires both POSIX and 3rd party/native GDI and GUI frameworks to create usable Linux and UNIX software. DOTNUTSHELL can create highly scalable and usable POSIX software which can be run on UNIX and Linux. The software can range from simple utilities to distributed software which has to be run on heterogenous platforms such as Linux, UNIX and Windows.

Linux and UNIX development is also the desired platform and framework for the creation of embedded software:

Embedded software and embedded systems, are those that require 100% of resources shared across a single platform often used to monitor, update and control hardware.

DOTNUTSHELL has experience in creating robust, efficient embedded software running as a monolithic Operating system, or a Kernel add-on in an Embedded Linux distribution.

It is the responsibility of the underlying embedded software system to maintain state information, persist changes to hardware configuration as well as gaurantee transaction and concurrency control at the hardware interface-level.

We have experience in creating:

MontaVista based embedded software

Embeddix based embedded software

Linux Driver creation

low-level hardware and bus interface strategies and mechanisms

I/O mapping and application/kernel space mixing

Real-time application development

Cross platform development

Assembler/C/C++ based embedded software development

POSIX development

RISC/PowerPC405 & 82xx, MIPS Development

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