An Introduction to PHP3
Listing 1 is two examples of PHP code to show some of its features. The first page accepts two numbers to add a first and last name. The passing of the form variables to be used in the next page happens automatically, which is one of the neatest things about PHP. This doesn't check their type—that they are actually numbers—in order to give an error. It does show the way PHP can be used to send and receive information to the user.
Listing 2 is an example that generates CGI variables on the fly, and the receiving page (Listing 3) deals with any incoming variables generated. If you run this in a PHP-enabled server, you'll see the variables passed in the cgi-call in the location line of the browser. All Listing 3 does is echo the names of the variables, but it demonstrates a technique that would enable a web site to generate a list on the fly and allow the user to make selections—like a shopping cart.
Now let's connect to a MySQL database. The following code would connect as root to a database named “stores” on the local host, with password “tiger”. It executes a query against a parts table, counts the number of rows in the query to check for the actual data, and if it exists, the result is displayed as an HTML table with check boxes to select items. Listing 4 is the PHP code preceded by the structure of the table. Note that knowing the number of rows is handy for determining whether to display the query at all (if there is any information) as well as counting down until no data is left. Each row of data is a row in an HTML table, with the fields walked through by number. The array containing the row from the query can be addressed by number or by field name, so you could also execute:
This can be advantageous during development when field positions in the table or query may be changing more often than names.
The next page of HTML (called in the FORM command) will receive the checked-off selections as CGI variables, which can be retrieved even though their names are unknown, using the technique shown above. It will then insert into another table the items that have been checked off. See Listing 5.
The latest information on installing PHP is available at http://www.php.net/ or in the distribution itself. I have installed it for FreeBSD, Linux and Win32 using their supplied packages. I have installed it only for Apache, although it is supposed to work with other web servers. It is supplied as source code for platforms other than Win32. The installation for Apache requires recompiling Apache to add it in as a module, although if that is not an option, it can be installed as a binary and scripts can be run as cgi-bin scripts.
I've found PHP3 to be a very enjoyable and versatile language for web applications. As of this writing, the next version—which is primarily billed as a performance improvement—is in beta testing. (PHP 4.0 includes the ZEND engine; see their web site for details.)
John Holland programs intranet applications as a consultant for Bell Atlantic. He lives outside Washington DC with his wife and children. He can be reached at email@example.com.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide