php man page for fflush

FFLUSH(3)								 1								 FFLUSH(3)

fflush - Flushes the output to a file

SYNOPSIS
       bool fflush (resource  $handle)

DESCRIPTION
	This function forces a write of all buffered output to the resource pointed to by the file $handle.

PARAMETERS
	      o $handle
		-The  file  pointer must be valid, and must point to a file successfully opened by fopen(3) or fsockopen(3) (and not yet closed by
		fclose(3)).

RETURN VALUES
	Returns TRUE on success or FALSE on failure.

EXAMPLES
       Example #1

	      File write example using fflush(3)

	      <?php
	      $filename = 'bar.txt';

	      $file = fopen($filename, 'r+');
	      rewind($file);
	      fwrite($file, 'Foo');
	      fflush($file);
	      ftruncate($file, ftell($file));
	      fclose($file);
	      ?>

SEE ALSO
       clearstatcache(3), fwrite(3).

PHP Documentation Group 														 FFLUSH(3)