Control your scripts with command-line PHP

PHP is most often used in combination with a Web server, to dynamically generate Web site pages. However, this Web server interface isn't the only way to use PHP, because the PHP distribution also includes a command-line interface which can be used to run PHP programs at the command prompt, much like Perl or bash.

This document will introduce you to PHP's command-line interface (CLI), showing you how to interact with PHP programs at the command prompt.

Executable
All PHP distributions, whether compiled from source or pre-built, include a PHP executable by default. This executable can be used to run command-line PHP programs.

To locate this executable on your system, use the following guidelines:

• On Windows, it will be stored in your main PHP installation folder as php.exe or (in older PHP versions) php-cli.exe.
• On Linux, it will be stored in the bin/ sub-directory of your PHP installation directory.

In either case, you can test it to ensure that it works, by calling it with the -v option:

shell> /path/to/php -v
PHP 5.0.0 (cli) (built: Jun  1 2005 18:32:10)
Copyright (c) 1997-2004 The PHP Group
Zend Engine v2.0.0, Copyright (c) 1998-2004 Zend Technologies

This should return the PHP version number.

A simple PHP CLI program
Once you've located the CLI executable, try it out with a simple program. Create a text file containing the following PHP code, and save it as hello.php:

<?php
echo "Hello from the CLI";
?>

Now, try running this program at the command prompt, by invoking the CLI executable and passing it the name of the script to run:

shell> /path/to/phphello.php
Hello from the CLI

Using standard input and output
The PHP CLI defines three constants, to make it easier to interact with the interpreter at the command prompt. These are shown in Table A.

Table A

Constant	Description
STDIN	The standard input device
STDOUT	The standard output device
STDERR	The standard error device

You can use these constants within your PHP script to accept user input, or display the results of processing and calculation. To understand this better, consider the following script: (Listing A)

Listing A
<?php
// ask for input
fwrite(STDOUT, "Enter your name: ");

// get input
$name = trim(fgets(STDIN));

// write input back
fwrite(STDOUT, "Hello, $name!");
?>

Look what happens when you run it:

shell> /path/to/phphello.php
Enter your name: Joe
Hello, Joe!

In this script, the fwrite() function first writes a message to the standard output device asking for the user's name. The user's input is then read into a PHP variable from the standard input device, and incorporated into a string. This string is then printed back to the standard output device with fwrite().

while (list($element, $waarde) = each($_POST)) {

		if (is_array($element)) {

			while (list($e, $w) = each($element)) {

				echo($e . " = " . $w. "<br>");

			}

		} else {

			if (!empty($waarde)) {

			echo($element . " = " . $waarde . "<br>");

			} else {

			echo($element . " is !Leeg!<br>");

			}

	   }

	}  

}

<?php

$S = fgets(STDIN);

$P = fgets(STDIN);

$k = fgets(STDIN);

echo "$s\n$P\n$k";

?>