Linux Unleashed, Third Edition:HTML Programming Basics





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Chapter 53HTML Programming Basics

by Tim Parker

In This Chapter
•   HTML authoring tools
•   Maintaining HTML
•   HTML programming basics

Having a Web server with nothing for content is useless, so you need to set up the information you will share through your Web system. This begins with Uniform Resource Locators (URLs), which are addresses to file locations. Anyone using your service only has to know the URL. You don’t need to have anything fancy. If you don’t have a special home page, anyone connecting to your system will get the contents of the Web root directory’s index.html file, or failing that, a directory listing of the Web root directory. That’s pretty boring, though, and most users want fancy home pages. To write a home page, you need to use HTML (HyperText Markup Language).
A home page is like a main menu. Many users may not ever see it because they can enter into any of the subdirectories on your system, or obtain files from another Web system through a hyperlink, without ever seeing your home page. However, many users want to start at the top, and that’s where your home page comes in. A home page file is usually called index.html. It is usually at the top of your Web source directories.
Writing an HTML document is not too difficult. The language uses a set of tags to indicate how the text is to be treated (such as headlines, body text, figures, and so on). The tricky part of HTML is getting the tags in the right place, without extra material on a line. HTML is rather strict about its syntax, so errors must be avoided to prevent problems.
In the early days of the Web, all documents were written with simple text editors. As the Web expanded, dedicated Web editors that understand HTML and the use of tags began to appear. Their popularity has driven developers to produce dozens of editors, filters, and utilities—all aimed at making a Web site producer’s life easier (as well as to ensure that the HTML language is properly used). HTML editors are available for many operating systems.
HTML Authoring Tools
You can write HTML documents in many ways: You can use an ASCII editor, a word processor, or a dedicated HTML tool. The choice of which method you use depends on personal preference and your confidence in HTML coding, as well as which tools you can easily obtain. Because many HTML-specific tools have checking routines or filters to verify that your documents are correctly laid out and formatted, they can be appealing. They also tend to be easier to use than non-HTML editors. On the other hand, if you are a veteran programmer or writer, you may want to stick with your favorite editor and use a filter or syntax checker afterwards.

You can use any ASCII editor to write HTML pages, including simple screen-oriented editors based on vi or emacs. They all enable you to enter tags into a page of text, but the tags are treated as words with no special meaning. There is no validity checking performed by simple editors, because they simply don’t understand HTML. There are some extensions for emacs and similar full-screen editors that provide a simple template check, but they are not rigorous in enforcing HTML styles.
If you wish to use a plain editor, you should carefully check your document for the valid use of tags. One of the easiest methods of checking a document is to import it into an HTML editor that has strong HTML tag checking. Another easy method is to simply call up the document on your Web browser and carefully study its appearance.
You can obtain a dedicated HTML authoring package from some sites, although they are not as common for Linux as they are for DOS and Windows (where there are literally dozens of such tools). If you are running both operating systems, you can always develop your HTML documents in Windows, and then import them to Linux. There are several popular HTML tools for Windows, such as HTML Assistant, HTMLed, and HoTMetaL. A few of the WYSIWYG editors are also available for X, and hence run under Linux, such as HoTMetaL. Some HTML authoring tools are fully WYSIWYG, while others are character-based. Most offer strong verification systems for generated HTML code.



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