Determine in php script if connected to internet?

Question 1

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.

Question 2

<?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;

}
?>

Question 3

To remove all the empty values from the comparison you can add array_diff():

if (count(array_unique(array_diff($check_post,array("")))) < count(array_diff($check_post,array(""))))

Question 4

The getActiveNetworkInfo() method of ConnectivityManager returns a NetworkInfo instance representing the first connected network interface it can find or null if none of the interfaces are connected. Checking if this method returns null should be enough to tell if an internet connection is available or not.

private boolean isNetworkAvailable() {
    ConnectivityManager connectivityManager 
          = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    return activeNetworkInfo != null && activeNetworkInfo.isConnected();
}

You will also need:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

in your android manifest.

Edit:

Note that having an active network interface doesn't guarantee that a particular networked service is available. Network issues, server downtime, low signal, captive portals, content filters and the like can all prevent your app from reaching a server. For instance you can't tell for sure if your app can reach Twitter until you receive a valid response from the Twitter service.

Question 5

You are right. The code you've provided only checks if there is a network connection. The best way to check if there is an active Internet connection is to try and connect to a known server via http.

public static boolean hasActiveInternetConnection(Context context) {
    if (isNetworkAvailable(context)) {
        try {
            HttpURLConnection urlc = (HttpURLConnection) (new URL("http://www.google.com").openConnection());
            urlc.setRequestProperty("User-Agent", "Test");
            urlc.setRequestProperty("Connection", "close");
            urlc.setConnectTimeout(1500); 
            urlc.connect();
            return (urlc.getResponseCode() == 200);
        } catch (IOException e) {
            Log.e(LOG_TAG, "Error checking internet connection", e);
        }
    } else {
        Log.d(LOG_TAG, "No network available!");
    }
    return false;
}

Of course you can substitute the http://www.google.com URL for any other server you want to connect to, or a server you know has a good uptime.

As Tony Cho also pointed out in this comment below, make sure you don't run this code on the main thread, otherwise you'll get a NetworkOnMainThread exception (in Android 3.0 or later). Use an AsyncTask or Runnable instead.

If you want to use google.com you should look at Jeshurun's modification. In his answer he modified my code and made it a bit more efficient. If you connect to

HttpURLConnection urlc = (HttpURLConnection) 
            (new URL("http://clients3.google.com/generate_204")
            .openConnection());

and then check the responsecode for 204

return (urlc.getResponseCode() == 204 && urlc.getContentLength() == 0);

then you don't have to fetch the entire google home page first.

Question 6

Try it like this:

<script type="text/javascript">var runFancy = true;</script>
<script>runFancy = true;</script>
<script type="text/javascript" src="menu.js"></script>
<!--[if IE]>
<script type="text/javascript">
runFancy = false;
</script> // <script type="text/javascript" src="iemenu.js"></script>
<![endif]-->

In this case menu.js will be loaded first and iemenu.js will be loaded afterwards. And if the functions are the same, the iefunction will overwrite the "normal" function and it should work.

Determine in php script if connected to internet?

Answers

php,internet-connection