Tells whether a file exists and is readable.
Path to the file.
Returns true if the file or directory specified by filename exists and is readable, false otherwise.
Exceptions and Errors
Upon failure, an E_WARNING is emitted.
Keep in mind that PHP may be accessing the file as the user id that the web server runs as (often 'nobody').
The results of this function are cached. See clearstatcache for more details.
As of PHP 5.0.0, this function can also be used with some URL wrappers. Refer to to determine which wrappers support stat family of functionality.
The check is done using the real UID/GID instead of the effective one.
This function may return true for directories. Use is_dir to distinguish file and directory.