fsync()

fsync() — Synchronizes changes to the file (including meta-data).

Built-in function of PHP 8.5. The manual lists it as available in PHP 8 >= 8.1.0. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

This function synchronizes changes to the file, including its meta-data. This is similar to fflush(), but it also instructs the operating system to write to the storage media.

Signature

fsync(resource $stream): bool

Parameters

Parameter	Type	What it takes
$stream	resource	The file pointer must be valid, and must point to a file successfully opened by fopen() or fsockopen() (and not yet closed by fclose()).

Return value

Returns true on success or false on failure.

Example

A runnable snippet:

$file = 'test.txt'; $stream = fopen($file, 'w'); fwrite($stream, 'test data'); fwrite($stream, "\r\n"); fwrite($stream, 'additional data'); fsync($stream); fclose($stream);