readfile() outputs the contents of a file directly to standard output. If PHP has been configured to be URL-aware, prefixing the filename with either http://orftp://opens a connection to the specified URL. Note that since the PHP URL wrappers don't support redirects, you have to append a trailing slash to directories. FTP connections must be made to servers with support for passive mode transfers.
Because some of the filesystem functions to read/write from files partially share the same code, one or more of the bugs reported elsewhere may also apply to this function.
3.0.8: Crashes when used with URLs on FreeBSD 3.2.
3.0.8, 3.0.9: Successive calls on URLs don't work on Solaris 2.5.1/Apache 1.3.6.
3.0.12: Reported not to retrieve all content (only about the first 1400 bytes) from some web servers, Linux 2.2.10 (not verified).
PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing (Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch). This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/). The authors of this book have elected not to choose any options under the OPL. This online book was obtained from http://www.fooassociates.com/phpfer/ and is designed to provide information about the PHP programming language, focusing on PHP version 4.0.4 for the most part. The information is provided on an as-is basis, and no warranty or fitness is implied. All persons and entities shall have neither liability nor responsibility to any person or entity with respect to any loss or damage arising from the information contained in this book.