PHP is a powerful open source server-sided scripting language that can be used on a wide variety of operating systems and webservers, including Apache on UNIX and IIS on Windows.
PHP contains numerous extensions which enable you to dynamically create images and flash files, parse xml, connect to remote servers using pop, imap, ftp, http and raw sockets, natively access many database servers including PostgreSql, MySQL and Microsoft SQL Server, compress and decompress files, lookup domain names and and much more.
PHP has an excellent manual and online documentation which covers every function for every extension available.
APC is the Alternative PHP Cache, which is a free, open, and robust framework for caching and optimizing PHP intermediate code. I posted about how to install APC on Linux a couple of days ago, and will now look at the apc.php script which comes with APC and shows information about how much of the cache is being used, what files are being cached, the number of times they’ve been accessed etc.
I’ve often found that something gets left out or forgotten when moving a website from an old server to a new install. I’ve just finished migrating one of my customer’s sites to a new CentOS 5.0 install with Apache 2.2 and PHP 5.1.6, and there’s one single PHP script in the site which uses the SoapClient class.
Naturally I’d forgotten to test this particular function until after the migration was complete, and was wondering why the script had failed. A quick look in the Apache error log file revealed the following error message: PHP Fatal error: "Class ‘SoapClient’ not found"
If you get the following error message in PHP then it means you need to have the XSL extension installed. Obviously the /path/to/file.php will be the actual path and filename of the PHP script the error occured in, and the line number will be the actual line. The PHP manual says that "PHP 5 includes the XSL extension by default" but one of my CentOS 5 installations it didn’t seem to be; the following post looks at how to install this extension on CentOS 5.
Fatal error: Class 'XsltProcessor' not found in /path/to/file.php on line 138
Many websites I have worked on have frequently modified CSS style sheets and Javascript library files. In order to prevent Javascript errors or layout and style issues caused by web browsers caching these files, I used to rename the file for each revision, and then modify the name of the CSS or JS file in my PHP header include files. This article looks out how I now do this using the modified timestamp of the file.
The PHP function tempnam() creates a file with a unique name. This can be useful if you need to output some data into a temporary file for one reason or another, and the actual name of the file is not important.
Unfortunately there is no pre-built module/extension for MSSQL for PHP in the Yum repositories for CentOS 5, so you need to build it yourself. It’s a reasonably simple process, but you do need to have gcc and php-devel packages already installed (and a whole bunch of others which I’ll list at the end of this post).