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filter is not described

wp_unique_filename filter-hook . WP 4.5.0

Filters the result when generating a unique file name.

Usage

add_filter( 'wp_unique_filename', 'filter_function_name_584', 10, 4 );
function filter_function_name_584( $filename, $ext, $dir, $unique_filename_callback ){
	// filter...

	return $filename;
}
$filename(string)
Unique file name.
$ext(string)
File extension, eg. ".png".
$dir(string)
Directory path.
$unique_filename_callback(callable/null)
Callback function that generates the unique file name.

Where the hook is called

wp_unique_filename()
wp-includes/functions.php 2111
return apply_filters( 'wp_unique_filename', $filename2, $ext, $dir, $unique_filename_callback );
wp-includes/functions.php 2126
return apply_filters( 'wp_unique_filename', $filename, $ext, $dir, $unique_filename_callback );

Where the hook is used (in WP core)

Does not used.