php://

php:// — Accessing various I/O streams

Description

PHP provides a number of miscellaneous I/O streams that allow access to

PHP's own input and output streams, the standard input, output and error

file descriptors, in-memory and disk-backed temporary file streams, and

filters that can manipulate other file resources as they are read from and

written to.

php://stdin, php://stdout and php://stderr

php://stdin, php://stdout and

php://stderr allow direct 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://stdin is read-only, whereas

php://stdout and php://stderr are

write-only.

php://input

php://input is a read-only stream that allows you to

read raw data from the request body. In the case of POST requests, it is

preferable to use php://input instead of $HTTP_RAW_POST_DATA as it does not depend

on special php.ini directives. Moreover, for those cases where

$HTTP_RAW_POST_DATA is not populated by default, it is a

potentially less memory intensive alternative to activating .

php://input is not available with

enctype="multipart/form-data".

Note:

A stream opened with php://input can only be read

once; the stream does not support seek operations. However, depending on

the SAPI implementation, it may be possible to open another

php://input stream and restart reading. This is only

possible if the request body data has been saved. Typically, this is the

case for POST requests, but not other request methods, such as PUT or

PROPFIND.

php://output

php://output is a write-only stream that allows you to

write to the output buffer mechanism in the same way as

print and echo.

php://fd

php://fd allows direct access to the given file

descriptor. For example, php://fd/3 refers to file

descriptor 3.

php://memory and php://temp

php://memory and php://temp are

read-write streams that allow temporary data to be stored in a file-like

wrapper. The only difference between the two is that

php://memory will always store its data in memory,

whereas php://temp will use a temporary file once the

amount of data stored hits a predefined limit (the default is 2 MB). The

location of this temporary file is determined in the same way as the

sys_get_temp_dir() function.

The memory limit of php://temp can be controlled by

appending /maxmemory:NN, where NN is

the maximum amount of data to keep in memory before using a temporary

file, in bytes.

php://filter

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 part of its path. Multiple filter chains can be specified on one path.

Please refer to the examples for specifics on using these parameters.

php://filter parameters Name Description

resource=<stream to be filtered>

This parameter is required. It specifies the stream that you would

like to filter.

read=<filter list to apply to read chain>

This parameter is optional. One or more filter names can be provided

here, separated by the pipe character (|).

write=<filter list to apply to write chain>

This parameter is optional. One or more filter names can be provided

here, separated by the pipe character (|).

<filter list to apply to both chains>

Any filter lists which are not prefixed by read=

or write= will be applied to both the read and

write chains as appropriate.

Options

Wrapper Summary (for php://filter, refer to the

summary of the wrapper being filtered)

Attribute Supported

Restricted by

No

Restricted by

php://input,

php://stdin,

php://memory and

php://temp only.

Allows Reading

php://stdin,

php://input,

php://fd,

php://memory and

php://temp only.

Allows Writing

php://stdout,

php://stderr,

php://output,

php://fd,

php://memory and

php://temp only.

Allows Appending

php://stdout,

php://stderr,

php://output,

php://fd,

php://memory and

php://temp only. (Equivalent to writing)

Allows Simultaneous Reading and Writing

php://fd,

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

Supports stream_select()

php://stdin,

php://stdout,

php://stderr,

php://fd and

php://temp only.

Changelog

Version Description

5.3.6

php://fd was added.

5.1.0

php://memory and php://temp

were added.

5.0.0

php://filter was added.

Examples

Example #1 php://temp/maxmemory

This optional parameter allows setting the memory limit before

php://temp starts using a temporary file.

Example #2 php://filter/resource=<stream to be filtered>

This parameter must be located at

the end of your php://filter specification and

should point to the stream which you want filtered.

Example #3 php://filter/read=<filter list to apply to read chain>

This parameter takes one or more

filternames separated by the pipe character |.

Example #4 php://filter/write=<filter list to apply to write chain>

This parameter takes one or more

filternames separated by the pipe character |.