D:\host\newselvi\id.php

<?php
header('Content-Type: text/plain');

echo "PHP SAPI: " . php_sapi_name() . PHP_EOL;
echo "get_current_user(): " . get_current_user() . PHP_EOL;
echo "USERNAME env: " . getenv('USERNAME') . PHP_EOL;

$pid = getmypid();
echo "PID: $pid" . PHP_EOL;

$test = __DIR__ . "\\wp-content\\uploads\\_perm_test.txt";
$r = @file_put_contents($test, "ok " . date("c"));
echo "Write test: " . ($r ? "SUCCESS" : "FAIL") . PHP_EOL;

if (!$r) {
  echo "Last error: ";
  var_export(error_get_last());
  echo PHP_EOL;
}