As long as allow_url_fopen is enabled in
php.ini, you can use HTTP and FTP
URLs with most of the functions
that take a filename as a parameter. In addition, URLs can be
used with the include(),
include_once(), require() and
require_once() statements.
See Appendix M for more information about the protocols
supported by PHP.
Note:
In PHP 4.0.3 and older, in order to use URL wrappers, you were required
to configure PHP using the configure option
--enable-url-fopen-wrapper.
For example, you can use this to open a file on a remote web server,
parse the output for the data you want, and then use that data in a
database query, or simply to output it in a style matching the rest
of your website.
Example 39-1. Getting the title of a remote page
<?php
$file = fopen ("http://www.example.com/", "r");
if (!$file) {
echo "<p>Unable to open remote file.\n";
exit;
}
while (!feof ($file)) {
$line = fgets ($file, 1024);
/* This only works if the title and its tags are on one line */
if (eregi ("<title>(.*)</title>", $line, $out)) {
$title = $out[1];
break;
}
}
fclose($file);
?>
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You can also write to files on an FTP server (provided that you
have connected as a user with the correct access rights). You
can only create new files using this method; if you try to overwrite
a file that already exists, the fopen() call will
fail.
To connect as a user other than 'anonymous', you need to specify
the username (and possibly password) within the URL, such as
'ftp://user:password@ftp.example.com/path/to/file'. (You can use the
same sort of syntax to access files via HTTP when they require Basic
authentication.)
Example 39-2. Storing data on a remote server
<?php
$file = fopen ("ftp://ftp.example.com/incoming/outputfile", "w");
if (!$file) {
echo "<p>Unable to open remote file for writing.\n";
exit;
}
/* Write the data here. */
fwrite ($file, $_SERVER['HTTP_USER_AGENT'] . "\n");
fclose ($file);
?>
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Note:
You might get the idea from the example above that you can use
this technique to write to a remote log file. Unfortunately
that would not work because the fopen() call will
fail if the remote file already exists. To do distributed logging
like that, you should take a look at syslog().
