PHP 3.0.13 and up, php://output and php://input since PHP 4.3.0, php://filter since PHP 5.0.0
php://stdin, php://stdout and php://stderr allow access to the corresponding input or output stream of the PHP process.
php://output allows you to write to the output buffer mechanism in the same way as print() and echo().
php://input allows you to read raw POST data. It is a less memory intensive alternative to $HTTP_RAW_POST_DATA and does not need any special php.ini directives.
php://stdin and php://input are read-only, whereas php://stdout, php://stderr and php://output are write-only.
php://filter is a kind of meta-wrapper designed to permit the application of filters to a stream at the time of opening. This is useful with all-in-one file functions such as readfile(), file(), and file_get_contents() where there is otherwise no opporotunity to apply a filter to the stream prior the contents being read.
The php://filter target takes the following 'parameters' as parts of its 'path'.
/resource=<stream to be filtered> (required) This parameter must be located at the end of your php://filter specification and should point to the stream which you want filtered.
<?php
/* This is equivalent to simply:
readfile("http://www.example.com");
since no filters are actually specified */
readfile("php://filter/resource=http://www.example.com");
?>/read=<filter list to apply to read chain> (optional) This parameter takes one or more filternames separated by the pipe character |.
<?php
/* This will output the contents of
www.example.com entirely in uppercase */
readfile("php://filter/read=string.toupper/resource=http://www.example.com");
/* This will do the same as above
but will also ROT13 encode it */
readfile("php://filter/read=string.toupper|string.rot13/resource=http://www.example.com");
?>/write=<filter list to apply to write chain> (optional) This parameter takes one or more filternames separated by the pipe character |.
<?php
/* This will filter the string "Hello World"
through the rot13 filter, then write to
example.txt in the current directory */
file_set_contents("php://filter/write=string.rot13/resource=example.txt","Hello World");
?>| Attribute | Supported |
|---|---|
| Restricted by allow_url_fopen. | No |
| Allows Reading | php://stdin and php://input only. |
| Allows Writing | php://stdout, php://stderr, and php://output only. |
| Allows Appending | php://stdout, php://stderr, and php://output only. (Equivalent to writing) |
| Allows Simultaneous Reading and Writing | No. These wrappers are unidirectional. |
| Supports stat() | No |
| Supports unlink() | No |
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