ftp_cdup

<?php 
// set up basic connection 
$ftp = ftp_connect($ftp_server); 

// login with username and password 
$login_result = ftp_login($ftp, $ftp_user_name, $ftp_user_pass); 

// change the current directory to html 
ftp_chdir($ftp, 'html'); 

echo ftp_pwd($ftp); // /html 

// return to the parent directory 
if (ftp_cdup($ftp)) { 
  echo "cdup successful\n"; 
} else { 
  echo "cdup not successful\n"; 
} 

echo ftp_pwd($ftp); // / 

ftp_close($ftp); 
?>