PHP Cookbook

18.17. Flushing Output to a File

Problem

You want to force all buffered data to be written to a filehandle.

Solution

Use fflush( ) :

fwrite($fh,'There are twelve pumpkins in my house.');
fflush($fh);

This ensures that "There are twelve pumpkins in my house.” is written to $fh.

Discussion

To be more efficient, system I/O libraries generally don’t write something to a file when you tell them to. Instead, they batch the writes together in a buffer and save all of them to disk at the same time. Using fflush( ) forces anything pending in the write buffer to be actually written to disk.

Flushing output can be particularly helpful when generating an access or activity log. Calling fflush( ) after each message to log file makes sure that any person or program monitoring the log file sees the message as soon as possible.

See Also

Documentation on fflush( ) at http://www.php.net/fflush.