When you use stat(), lstat(), 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() function to clear the
information that PHP caches about a file.
注: This function caches information about specific filenames, so you only need to call clearstatcache() if you are performing multiple operations on the same filename and require the information about that particular file to not be cached.
Affected functions include
stat(), lstat(),
file_exists(), is_writable(),
is_readable(),
is_executable(),
is_file(), is_dir(),
is_link(),
filectime(), fileatime(),
filemtime(), fileinode(),
filegroup(), fileowner(),
filesize(), filetype(), and
fileperms().