Read request body sent from LINE App

read_post_line_app.php

<?php
$raw = file_get_contents('php://input');
file_put_contents('/tmp/log_line_' . date('YYmmdd'), $raw . PHP_EOL, FILE_APPEND);

// ログ確認方法
// https://example.com?log=1
$log = filter_input(INPUT_GET, 'log', FILTER_SANITIZE_URL);
if ($log) {
  $handle = popen("tail -f /tmp/log_line_" . date("YYmmdd") . " 2>&1", 'r');
  while(!feof($handle)) {
      $buffer = fgets($handle);
      echo "$buffer<br/>\n";
      ob_flush();
      flush();
  }
  pclose($handle);
}