Correction

composer.json

@@ -16,6 +16,6 @@
     }
   },
   "scripts": {
-    "post-update-cmd": "Opawg\\UserAgent\\UserAgentsGenerate::generate"
+    "post-update-cmd": "php src/UserAgentsGenerate.php > src/UserAgents.php"
   }
 }

src/UserAgentsGenerate.php

-<?php
-namespace Opawg\UserAgents;
+#!/usr/bin/php
 
-class UserAgentsGenerate {
-    public static function generate()
-    {
+<?php
 /*
 * Load json and convert it to PHP object:
 */
@@ -55,5 +52,3 @@ EOT;
 print $rowstr;
 print ";\n";
 print "}\n";
-    }
-}