MidwestWebDeveloper.com: personal blog from a professional web developer. ramblings about code, etc.

<?php 

function httpscheck($url = '')
{
  if($_SERVER['HTTPS'] != "on" || $_SERVER['HTTP_PORT'] != 443)
  {
    if(strlen($url) == 0)
    {
      $url = $_SERVER['REQUEST_URI'];
    }
    if(headers_sent())
    {
      trigger_error('SSL redirect failed as HTTP headers were previously sent to the browser', E_NOTICE);
    }
    else
    {
      die(header('Location: ' . $url));
    }
  }
}

<?php

if(isset($_GET['set']) && $_GET['set'] != 'yes')
{
  // Set cookie
  setcookie('test', 'test', time() + 60);

  // Reload page
  header("Location: cookie.php?set=yes");
  exit ;
}
else
{
  // Check if cookie exists
  if(isset($_GET['set']) && ! empty($_COOKIE['test']))
  {
    echo "Cookies are enabled on your browser";
  }
  else
  {
    echo "Cookies are <b>NOT</b> enabled on your browser";
  }
}
?>

<?php

$curl_errors = array();
$curl_errors[0] = "CURL_OK";
$curl_errors[1] = "CURL_UNSUPPORTED_PROTOCOL";
$curl_errors[2] = "CURL_FAILED_INIT";
$curl_errors[3] = "CURL_URL_MALFORMAT";
$curl_errors[4] = "CURL_URL_MALFORMAT_USER";
$curl_errors[5] = "CURL_COULDNT_RESOLVE_PROXY";
$curl_errors[6] = "CURL_COULDNT_RESOLVE_HOST";
$curl_errors[7] = "CURL_COULDNT_CONNECT";
$curl_errors[8] = "CURL_FTP_WEIRD_SERVER_REPLY";

?>

<?php

function bustcache()
{
  if(headers_sent())
  {
    trigger_error('Already sent HTTP headers, not busting the cache', E_NOTICE);
  }
  else
  {
    header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');
    header('Last-Modified: ' . gmdate("D, d M Y H:i:s") . ' GMT');
    header('Cache-Control: no-cache, must-revalidate');
    header('Pragma: no-cache');
  }
}

?> 

The above is a very simple function for preventing a browser from caching content.  This isn't recommended on static sites, but is exceptionally helpful when building dynamic applications. Simply call this function before any output.

Shutter is one of my favorite Linux programs. It does what Windows' Snipping Tool does, plus a lot more.

One of the functions I really like is being able to edit screen shots; annotation, arrows, circles, whatever you need to illustrate the screenshot.

Recently I upgraded a machine to Ubuntu 10.04 and found that the edit button was grayed out --- Shutter would no longer let me edit any screenshots.

Thankfully, the fix was simple:

sudo apt-get install libgoo-canvas-perl

This is nowhere near an all inclusive list of things you can do to make your life easier when having to maintain a website.  These are just a few tips and tricks worth knowing.

1) Never use absolute paths.  Use relative paths instead.

For example, this is a no-no:

include('/home/user/public_html/some/file');

Instead, try this:

include($_SERVER['DOCUMENT_ROOT'] . '/some/file');

Or even this:

include('../../some/file');

Then if (when!) you migrate to a new server, and your base web dir changes, you won't have to update your file paths throughout your code.

2) Use a config file.

Don't hard code your email address throughout your site.  define() it in a config file that you include() everywhere.  Same goes for mysql credentials, or any other text which may need to change at some point.  Putting everything in an external config makes a migration much easier.

Example:

define('EMAIL','my@email.com');
define('DB_USER','mydbusername');
define('DB_PASS','mydbpassword'); 

Or, use global variables:

$GLOBALS['EMAIL'] = 'my@email.com';
$GLOBALS['DB_USER'] = 'mydbusername';
$GLOBALS['DB_PASS'] = 'mydbpassword'; 

3) Place re-used web page code into external files. include() them.

Got a navigation menu that appears on every page?  Place it into a file (e.g. navigation.php) and include() it on every page.

Google Analytics?  Same deal--- include() it.

Doing so makes site maintenance MUCH easier.

if(isset($_SERVER['REMOTE_ADDR']))
{
    die();
}

If you have a script that needs to run from the command line (say, via cron), but for some dumb reason needs to reside in a publicly accessible location (e.g. via the web), use the above code at the very start of your script.  The only time that particular variable exists is when someone is connecting over the web.  Command line execution doesn't create it.

If you have a script that requires a random pause delay --- for example, perhaps a web scraper --- here's a super simple way to do it.

usleep(rand(1000,3000));

The rand() function is being fed two numbers; the lowest number to generate, and the highest.

The usleep() function causes a script to pause for a specified number of microseconds.

So the code above is saying "randomly sleep between 1000-3000 microseconds", which means 1-3 actual seconds.

Simple, and effective!

This is one I forget all the time, so I figure I may as well document it here.

var randomnumber=Math.floor(Math.random()*1001)

"1001" means any number between 0 and 1000 will be generated. So for instance, change it to 101 if you want to use 0-100 as a range. And so forth.

Ubuntu comes with some pretty decent screensavers.  

If you want even more --- alot more -- install the 'xscreensaver-data-extra' package.

For example, from the command line, type:

sudo apt-get install xscreensaver-data-extra

Enjoy!

If you have a command that you need run at startup, here's a real simple way to do it.

Simply add this to your crontab:

@reboot /path/to/command

Now the next time you reboot your machine, the command will always be run for you.