move_uploaded_file()

bool move_uploaded_file ( string $filename , string $destination )
This function checks to ensure that the file designated by filename is a valid upload file (meaning that it was uploaded via PHP’s HTTP POST upload mechanism). If the file is valid, it will be moved to the filename given by destination.

<?php
if($_FILES&#91;'file'&#93;){
  move_uploaded_file($_FILES&#91;'file'&#93;&#91;'tmp_name'&#93;, './img/test.jpg');
}
?>

<form action="./index.php" method="POST" enctype="multipart/form-data">
  <input type="file" name="faile">
  <input type="submit" value="ファイルをアップロードする">
</form>

php error

<?php
try{
  if(is_uploaded_file($_FILES&#91;'file'&#93;&#91;'tmp_name'&#93;)){
    move_uploaded_file($_FILES&#91;'file'&#93;&#91;'tmp_name'&#93;, './img/test.jpg');
  }
} catch(Exception $e){
  echo 'エラー:', $e->getMessage().PHP_EOL;
}
?>

<form action="./index.php" method="POST" enctype="multipart/form-data">
  <input type="file" name="file">
  <input type="submit" value="ファイルをアップロードする">
</form>

php form

php.init
file_uploads, post_max_size, upload_max_filesize, memory_limit, max_execution_time, upload_tmp_dir, max_file_uploads

Tells whether the file was uploaded via HTTP POST