检索文件并将其写入系统

Question

What's the simplest way in PHP, to:

1. Retrieve a file from an external URL (http://test.com/thisfile)?

2. If successful, delete local file /root/xml/test.xml.

3. Rename downloaded file to test.xml.

4. Write new file to /root/xml/ folder.

This will be a private script, so security or error handling are not important concerns.

Answer 1

$contents = file_get_contents( 'http://test.com/testfile' );
if( $contents ) {
     $file = '/root/xml/test.xml';
     unlink( $file );
     file_put_contents( $contents, $file ); 
}