Fixes #4483 - thanks for the report that's really useful as loads of …

…users are on cpanel and hostgator!

Also updated the doc at: http://piwik.org/docs/setup-auto-archiving/#cpanel-how-to-set-up-the-cron-script-using-cpanel
and removed http:// in the cpanel examples..

core/CronArchive.php

@@ -840,7 +840,7 @@ private function initTokenAuth()
 
     private function initPiwikHost()
     {
-        // If archive.php run as a web cron, we use the current hostname
+        // If archive.php run as a web cron, we use the current hostname+path
         if (!Common::isPhpCliMode()) {
             // example.org/piwik/misc/cron/
             $piwikUrl = Common::sanitizeInputValue(Url::getCurrentUrlWithoutFileName());
@@ -849,12 +849,19 @@ private function initPiwikHost()
         } else {
             // If archive.php run as CLI/shell we require the piwik url to be set
             $piwikUrl = $this->isParameterSet("url", true);
-            if (!$piwikUrl
-                || !\Piwik\UrlHelper::isLookLikeUrl($piwikUrl)
-            ) {
-                $this->logFatalError("archive.php expects the argument --url to be set to your Piwik URL, for example: --url=http://example.org/piwik/ "
-                    . "\n--help for more information", $backtrace = false);
+
+            if (!$piwikUrl) {
+                $this->logFatalErrorUrlExpected();
+            }
+
+            if(!\Piwik\UrlHelper::isLookLikeUrl($piwikUrl)) {
+                // try adding http:// in case it's missing
+                $piwikUrl = "http://" . $piwikUrl;
+            }
+            if(!\Piwik\UrlHelper::isLookLikeUrl($piwikUrl)) {
+                $this->logFatalErrorUrlExpected();
             }
+
             // ensure there is a trailing slash
             if ($piwikUrl[strlen($piwikUrl) - 1] != '/') {
                 $piwikUrl .= '/';
@@ -1086,5 +1093,11 @@ protected function setSiteIsArchived($idsite)
             }
         }
     }
+
+    private function logFatalErrorUrlExpected()
+    {
+        $this->logFatalError("archive.php expects the argument --url to be set to your Piwik URL, for example: --url=http://example.org/piwik/ "
+            . "\n--help for more information", $backtrace = false);
+    }
 }