Determine in php script if connected to internet?

Question

How can I check if I'm connected to the internet from my PHP script which is running on my dev machine?

I run the script to download a set of files (which may or may not exist) using wget. If I try the download without being connected, wget proceeds to the next one thinking the file is not present.

Answer 1

<?php
function is_connected()
{
    $connected = @fsockopen("www.example.com", 80); 
                                        //website, port  (try 80 or 443)
    if ($connected){
        $is_conn = true; //action when connected
        fclose($connected);
    }else{
        $is_conn = false; //action in connection failure
    }
    return $is_conn;

}
?>

Answer 2

You can always ping good 'ol trusty google:

$response = null;
system("ping -c 1 google.com", $response);
if($response == 0)
{
    // this means you are connected
}

Answer 3

This code was failing in laravel 4.2 php framework with an internal server 500 error:

<?php
     function is_connected()
     {
       $connected = @fsockopen("www.some_domain.com", 80); 
        //website, port  (try 80 or 443)
       if ($connected){
          $is_conn = true; //action when connected
          fclose($connected);
       }else{
         $is_conn = false; //action in connection failure
       }
      return $is_conn;
    }
?>

Which I didn't want to stress myself to figure that out, hence I tried this code and it worked for me:

function is_connected()
{
  $connected = fopen("http://www.google.com:80/","r");
  if($connected)
  {
     return true;
  } else {
   return false;
  }

} 

Please note that: This is based upon the assumption that the connection to google.com is less prone to failure.

Answer 4

The accepted answer did not work for me. When the internet was disconnected it threw a php error. So I used it with a little modification which is below:

if(!$sock = @fsockopen('www.google.com', 80))
{
    echo 'Not Connected';
}
else
{
echo 'Connected';
}