PHP input/output streams

php://stdin, php://stdout and php://stderr allow access to the corresponding input or output stream of the PHP process. The stream references a duplicate file descriptor, so if you open php://stdin and later close it, you close only your copy of the descriptor--the actual stream referenced by STDIN is unaffected. Note that PHP exhibited buggy behavior in this regard until PHP 5.2.1. It is recommended that you simply use the constants STDIN, STDOUT and STDERR instead of manually opening streams using these wrappers.

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://input is not available with enctype="multipart/form-data".

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'.

The php://memory wrapper stores the data in the memory. php://temp behaves similarly, but uses a temporary file for storing the data when a certain memory limit is reached (the default is 2 MB).

The php://temp wrapper takes the following 'parameters' as parts of its 'path':

Table N-6. Wrapper Summary (For php://filter, refer to summary of wrapper being filtered.)

AttributeSupported
Restricted by allow_url_fopenNo
Restricted by allow_url_include php://input, php://stdin, php://memory and php://temp only.
Allows Reading php://stdin, php://input, php://memory and php://temp only.
Allows Writing php://stdout, php://stderr, php://output, php://memory and php://temp only.
Allows Appending php://stdout, php://stderr, php://output, php://memory and php://temp only. (Equivalent to writing)
Allows Simultaneous Reading and Writing php://memory and php://temp only.
Supports stat() php://memory and php://temp only.
Supports unlink()No
Supports rename()No
Supports mkdir()No
Supports rmdir()No