php man page for clearstatcache

CLEARSTATCACHE(3)							 1							 CLEARSTATCACHE(3)

clearstatcache - Clears file status cache

SYNOPSIS
       void clearstatcache ([bool  $clear_realpath_cache = false], [string  $filename])

DESCRIPTION
	When  you  use	stat(3), lstat(3), or any of the other functions listed in the affected functions list (below), PHP caches the information
       those functions return in order to provide faster performance. However, in certain cases, you may want to clear the cached information. For
       instance,  if  the same file is being checked multiple times within a single script, and that file is in danger of being removed or changed
       during that script's operation, you may elect to clear the status cache. In these cases, you can  use  the  clearstatcache(3)  function	to
       clear the information that PHP caches about a file.

	You  should  also  note that PHP doesn't cache information about non-existent files. So, if you call file_exists(3) on a file that doesn't
       exist, it will return FALSE until you create the file. If you create the file, it will return TRUE even if you then delete the  file.  How-
       ever unlink(3) clears the cache automatically.

       Note

	       This  function caches information about specific filenames, so you only need to call clearstatcache(3) if you are performing multi-
	      ple operations on the same filename and require the information about that particular file to not be cached.

	Affected functions include stat(3), lstat(3), file_exists(3), is_writable(3),  is_readable(3),	is_executable(3),  is_file(3),	is_dir(3),
       is_link(3), filectime(3), fileatime(3), filemtime(3), fileinode(3), filegroup(3), fileowner(3), filesize(3), filetype(3), and fileperms(3).

PARAMETERS
	      o $clear_realpath_cache
		- Whether to clear the realpath cache or not.

	      o $filename
		- Clear the realpath and the stat cache for a specific filename only; only used if $clear_realpath_cache is TRUE.

RETURN VALUES
	No value is returned.

CHANGELOG
       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.3.0	|						    |
       |	|						    |
       |	|  Added  optional $clear_realpath_cache and $file- |
       |	| name parameters.				    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES
       Example #1

	      clearstatcache(3) example

	      <?php
	      $file = 'output_log.txt';

	      function get_owner($file)
	      {
		  $stat = stat($file);
		  $user = posix_getpwuid($stat['uid']);
		  return $user['name'];
	      }

	      $format = "UID @ %s: %s
";

	      printf($format, date('r'), get_owner($file));

	      chown($file, 'ross');
	      printf($format, date('r'), get_owner($file));

	      clearstatcache();
	      printf($format, date('r'), get_owner($file));
	      ?>

	      The above example will output something similar to:

	      UID @ Sun, 12 Oct 2008 20:48:28 +0100: root
	      UID @ Sun, 12 Oct 2008 20:48:28 +0100: root
	      UID @ Sun, 12 Oct 2008 20:48:28 +0100: ross

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