PHP in the Shell

PHP may be most commonly used within a web server to produce web pages, but it is a powerful scripting engine by itself. PHP is an amazingly useful multipurpose tool when used from the command line. This post will show you how to use the PHP Command Line Interface (CLI). Some of the information here is Linux specific, but there are equivalents for Windows.

Accessing the PHP CLI

Obviously the first thing you need to know is how to run PHP from the command line. There are a number of ways to do this, and one way that I prefer.

The method I find easiest is to write your script as a shell script. This basically means taking a regular PHP script and adding a line to the beginning declaring the php binary to interpret the script. Here's an example:

#!/usr/bin/php
<?php
echo 'Hello World';
?>

Assuming the file name 'test.php' you would make it executable with chmod +x test.php and run it simply with ./test.php. Note that the file does not need to end with .php to function.

Other options for accessing the PHP CLI are to pass scripts or code to php as parameters, pass code to php through standard input, or enter code manually in interactive mode.

File as parameter:

$ php test.php

Code as parameter:

$ php -r "echo 'Hello World';"

Code through standard input (generate_php_code outputs code):

$ generate_php_code | php

Interactive mode:

$ php -a
Interactive shell
 
php > echo 'Hello World';
Hello World
php >

Using Arguments

Like any shell scripts, you can pass arguments to your PHP scripts. Accessing these arguments is very easy, since they are stored in an array called $argv. The number of arguments is stored in $argc.

To illustrate this, running the following script as ./args.php arg1 arg2 arg3:

#!/usr/bin/php
<?php
var_dump($argv);
?>

will output:

array(4) {
  [0]=>
  string(8) "args.php"
  [1]=>
  string(4) "arg1"
  [2]=>
  string(4) "arg2"
  [3]=>
  string(4) "arg3"
}

Practical Example

In this example, we'll create a script that outputs the number of days since a particular date. It will accept 3 parameters, the month, day, and year as numbers.

#!/usr/bin/php
<?php
if($argc < 4 || !is_numeric($argv[1]) || !is_numeric($argv[2]) || !is_numeric($argv[3]))
{
    echo "Usage: $argv[0] mm dd yyyy\n";
}
else
{
    $pastdate = mktime(0, 0, 0, $argv[1], $argv[2], $argv[3]);
    $diff = time() - $pastdate;
    $days = round($diff/60/60/24);
    echo "$days days since $argv[1]/$argv[2]/$argv[3]\n";
}
?>

$ ./days 11 17 1988
7699 days since 11/17/1988

Standard Input/Output

PHP also makes it fairly easy to work with standard input and output. It even provides the constants STDIN, STDOUT, and STDERR that point to the already opened streams to stdin, stdout, and stderr respectively. You use them exactly as you would a handle to an open file.

Here's an example to demonstrate the usage. This shows how to read STDIN line by line:

#!/usr/bin/php
<?php
// treat STDIN like a file handle
while(!feof(STDIN))
{
    $line = fgets(STDIN);
}
?>

Practical Example

This example script takes a file list (generated by ls) and outputs an HTML table:

#!/usr/bin/php
<?php
echo '<table>';
echo '<tr><th>Perm</th><th>Links</th><th>User</th><th>Group</th><th>Size</th><th>Date</th><th>Time</th><th>Name</th></tr>';
while(!feof(STDIN))
{
    $line = fgets(STDIN);
    $fields = preg_split('#\s+#', $line, 8);
    echo '<tr>';
    foreach($fields as $field)
    {
        echo '<td>' . $field . '</td>';
    }
    echo '</tr>';
}
echo '</table>';
?>

Assuming the name 'ls2html' use this to generate an HTML formatted table of the file list in list.htm:

$ ls -l | sed 1d | ./ls2html > list.htm

Conclusion

The PHP CLI is a very powerful tool that can be put to many uses. This can be very useful for someone like me who has strong PHP skills, but lacks strong Bash skills. As you can see, there's really not much difference between scripting for the web and scripting for the command line.

Similar Posts:

• Accessing the Command Line From PHP
• Creating a CAPTCHA in PHP with GD
• Using SSH in PHP

About Steve

Steve is the owner of UltraMega Tech. He is a freelance Web designer and developer who specializes in PHP and AJAX development.