WordPress Filesystem Tutorial

wpfilesystem-demo.php

<?php 
/* 
Plugin Name: Filesystem Tutorial
Description: Demo Plugin for http://ottopress.com/2011/tutorial-using-the-wp_filesystem
Plugin URL: http://ottopress.com/2011/tutorial-using-the-wp_filesystem
Author: otto42

DO NOT USE THIS ON A PRODUCTION SITE. THIS IS DEMONSTRATION CODE ONLY.
*/

// add the admin options page
add_action('admin_menu', 'otto_admin_add_page');

function otto_admin_add_page() {
	add_theme_page('Otto Test Page', 'Otto Test Options', 'edit_theme_options', 'otto', 'otto_options_page');
}

function otto_options_page() {
	if ( otto_check_buttons() ) return;
?>
<div>
<h2>My custom options page</h2>
<form action="" method="post">
<?php wp_nonce_field(); ?>
<input name="save" type="submit" value="Save a file" />
</form></div>
<?php
}

function otto_check_buttons() {
	if (empty($_POST)) return false;
	
	check_admin_referer();
	
	$form_fields = array ('save'); // this is a list of the form field contents I want passed along between page views
	$method = ''; // Normally you leave this an empty string and it figures it out by itself, but you can override the filesystem method here
	
	// check to see if we are trying to save a file
	if (isset($_POST['save'])) {
		// okay, let's see about getting credentials
		$url = wp_nonce_url('themes.php?page=otto');
		if (false === ($creds = request_filesystem_credentials($url, $method, false, false, $form_fields) ) ) {
		
			// if we get here, then we don't have credentials yet,
			// but have just produced a form for the user to fill in, 
			// so stop processing for now
			
			return true; // stop the normal page form from displaying
		}
			
		// now we have some credentials, try to get the wp_filesystem running
		if ( ! WP_Filesystem($creds) ) {
			// our credentials were no good, ask the user for them again
			request_filesystem_credentials($url, $method, true, false, $form_fields);
			return true;
		}
		
		// get the upload directory and make a test.txt file
		$upload_dir = wp_upload_dir();
		$filename = trailingslashit($upload_dir['path']).'test.txt';

		// by this point, the $wp_filesystem global should be working, so let's use it to create a file
		global $wp_filesystem;
		if ( ! $wp_filesystem->put_contents( $filename, 'Test file contents', FS_CHMOD_FILE) ) {
			echo "error saving file!";
		}
	}
	
	return true;
}