file_exits error - reproduction try

<?php

// create random file name
$file = '/tmp/' . uniqid();

// the file doesn't exist yet
var_dump(file_exists($file)); // false

// create the file
file_put_contents($file, 'test');
var_dump(file_exists($file)); // true

// as the manual points out, unlink will clear the cache
// use the shell to remove the file
`rm '$file'`;

// can return true when results get cached
if(file_exists($file)) {
    // behaviour like mentioned in PHP documentation
    echo 'error'; // never happended at my machine
}