PHP input/output streams

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 opportunity 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'.

Table I-5. Wrapper Summary (For php://filter, refer to summary of wrapper being filtered.)

AttributeSupported
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 WritingNo. These wrappers are unidirectional.
Supports stat()No
Supports unlink()No