Old-school PHP debugger

debug.php

<?php

/**
 * Print out argument to log file - note, arrays, objects are printed via var_dump()
 * Useful for debugging an application where the logging implementation isn't great
 */
function d($msg) {
  $bt = debug_backtrace();
  $caller_bt = $bt[0];
  $filename = basename($caller_bt['file']);
  $loc = "[$filename:$caller_bt[line]] ";
  if (!is_string($msg)) {
    $val = ini_set('html_errors', 0);
    ob_start();
    var_dump($msg);
    $msg = ob_get_clean();
    ini_set('html_errors', $val);
  }
  file_put_contents('/tmp/php-debug.log', $loc.$msg.PHP_EOL, FILE_APPEND);
}

/**
 * Print out a backtrace
 */
function dtrace($msg) {
  ob_start();
  $old = ini_set('html_errors', 'off');
  if (!function_exists('xdebug_print_function_stack')) {
    echo $msg, PHP_EOL;
    debug_print_backtrace();
  }
  else {
    xdebug_print_function_stack($msg);
  }
  ini_set('html_errors', $old);
  $out = ob_get_clean();
  d($out);
}

/**
 * Return a debug backtrace (safe to use on production)
 */
function dpbtrace() {
  ob_start();
  debug_print_backtrace();
  $out = ob_get_clean();

  return $out;
}


// Example usage:
// Drupal: add to /sites/default/settings.php
// Moodle: add to /config.php
// make sure to create the target log file `/tmp/php-debug.log`, you might need to chown this to be the `www-data` user/group to allow PHP to write to it
// simply call d(); for anything you want to view in the logs - e.g. d($my_variable); or d('useful degug comment');
d('--------------- new bootstrap initiated -------------------');

/*
// e.g.
touch /tmp/php-debug.log
chmod 775 /tmp/php-debug.log
chown www-data:www-data /tmp/php-debug.log
wget https://gist.githubusercontent.com/ryanellis/0ee6152494117457d6739d96a6932476/raw -O debug.php
php -r 'require_once("debug.php"); d(array("some", "stuff", "here", 1, 2, 3));'
cat /tmp/php-debug.log
[debug.php:56] --------------- new bootstrap initiated -------------------

[Command line code:1] array(6) {
  [0]=>
  string(4) "some"
  [1]=>
  string(5) "stuff"
  [2]=>
  string(4) "here"
  [3]=>
  int(1)
  [4]=>
  int(2)
  [5]=>
  int(3)
}
*/

/*
Useful command to append directly to Moodle config.php file
touch /tmp/php-debug.log
chmod 775 /tmp/php-debug.log
chown www-data:www-data /tmp/php-debug.log

wget https://gist.githubusercontent.com/ryanellis/0ee6152494117457d6739d96a6932476/raw -O - | tail -n +2 >> config.php
*/