Realtime keystrokes in php bash scripts

keystrokes.php

#!/usr/bin/php
<?php

$trap = [];
system("xinput list | grep -Po 'id=\K\d+(?=.*slave\s*keyboard)' \
        | xargs -P0 -n1 xinput test > keys &");

while (true){
  $data = file("keys");
  $key = $data;
  array_push($trap,$key);
  if ((@strpos(implode($trap[count($trap)-1]), 'press   36') !== false)){
    echo "[+] return!";
    $trap = [];
    file_put_contents("keys", "");
  }
  if ((@strpos(implode($trap[count($trap)-1]), 'press   37') !== false)){
    echo "\n[+] left ctrl!";
    $trap = [];
    file_put_contents("keys", "");
  }
  usleep(10000); /* <- CAUTION */
}

//🜛 keycodes list:
//🜛 xmodmap -pke | less

This base script will detect RETURN and LEFT CTRL keys press from php.
Can be adapted for any keys.
Require linux tools, any x env.
NO ROOT
It listen for keystrokes globally, the focus can be outside the shell window