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vineri, 7 ianuarie 2011

The Top Ten Concepts for Linux Beginners - Number 8, Programming Language Support

Damn Small Linux can be an ideal platform for supporting a wide range of programming languages. You can even program directly from the command line via a programming shell such as Bash. Major programming languages used in this environment include C, C++, and Java. If you are developing for the Internet you may want to use PHP, a web programming language and MySQL, a language for database system development. All these programming languages are also available in the Windows environment. So the question arises, why would you want to program under Linux rather than under Windows?
Many web developers and Internet service providers feel that Linux provides a more stable web site environment than does Windows. The most widely used web server, Apache, is available under both these operating systems but its new features, security enhancements, and bug fixes always are made available first on the Open Source (LAMP) version. And then they filter down to the Windows version. At the time of this writing the Windows version of Apache has problems with its cryptographic functions.
While programming languages are essentially the same across these two operating systems, their libraries are quite different. Basically, when you write complicated programs you want to make use of as much prewritten software as possible to reduce your programming and debugging effort. One example is handling the graphical user interface. As programmers often say, why reinvent the wheel? Linux provides a wider choice of libraries and graphical user interface toolkits.
When you program in Linux it is often fairly easy to port your programs to the Windows environment. Unfortunately, the inverse is rarely true. Of course as Linux systems become more popular, you will find more and more Windows-based programming systems that enable you to convert your programs to run under Linux. To do so makes clear economic sense.
Program conversion tools may be fairly difficult to develop. For example, executing programs must access the actual computer hardware. As you may imagine Linux and Windows programs access hardware quite differently. The modules that manage hardware access are called drivers. Linux drivers tend to be of higher quality than Windows drivers.
These two operating systems differ substantially in the way they manage programs during their execution. In other articles we discussed Linux's increased security compared to Windows. We conclude this article by repeating a point that we have often made; you can run Damn Small Linux and its associated applications on very reduced hardware. You can do Linux, PHP, and MySQL development on old computers, ones that may have seemed ready for the garbage heap. In contrast many Windows competitors such as SQL Server Developer Edition require substantially more powerful computers, the kind of computers that people purchase for one or a few thousand dollars. When your programs will be used by dozens of people simultaneously, you will need powerful hardware. Don't forget the operating system; can you guess which one we recommend? Our next subject is the graphical user interface.
Read more: http://www.articlesbase.com/computers-articles/the-top-ten-concepts-for-linux-beginners-number-8-programming-language-support-652795.html#ixzz1ALJfTugE
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The Top Ten Concepts for Linux Beginners - Number 7, Shells and Utilities

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.
Read more: http://www.articlesbase.com/computers-articles/the-top-ten-concepts-for-linux-beginners-number-7-shells-and-utilities-640317.html#ixzz1ALHGRNpc
Under Creative Commons License: Attribution

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