PHP

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PHP (PHP Hypertext Preprocessor) is a scripting language designed for use in Web pages. PHP-enabled pages allow you to create dynamic Web pages that can perform tasks instead of just displaying data. PHP is an official project of the Apache Software Foundation. You can find out more about PHP at www.php.net.

Unlike CGI programs, which are executed separately from a Web page, PHP commands are embedded as tags within the page itself, much as SSI commands are. PHP support to interpret and execute these commands is provided directly by the Web server. This embedded support is enabled in Apache with the mod_php module (/etc/httpd/conf.d/php.conf configuration file). Instead of having to separately construct programs to be invoked and run outside the Web server, with PHP, such commands are embedded within a Web page and run by the Web server. The Web server maintains complete control at all times whenever tasks are being performed. It is possible, however, to implement PHP in a CGI mode, where PHP pages are constructed as separate programs, invoked by a Web page much as a Perl-based CGP program is.

PHP has flexible and powerful programming capabilities on the same level as C and Perl. As in those languages, you can create control structures such as if statements and loops. In addition, PHP has capabilities specifically suited to Web page tasks. PHP can interact directly with databases such as Oracle, MySQL, and IBM DB2. It can easily interact with all the standard protocols, such as IMAP, LDAP, HTTP, and POP3. It even has text processing abilities such as interpreting regular expressions and displaying XML documents. There are also extensions for searches, compression tools like gzip, and language translations. PHP supports a massive collection of possible operations. Check its Web site for a complete listing, as well as online manuals and tutorials.

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