php://Accessing various I/O streams DescriptionPHP 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 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.
php://input is not available in POST requests with
php://outputphp://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://fdphp://fd allows direct access to the given file descriptor. For example, php://fd/3 refers to file descriptor 3. php://memory and php://tempphp://memory and php://temp are read-write streams that allow temporary data to be stored in a file-like wrapper. One 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 Caution
Some PHP extensions may require a standard IO stream, and may attempt to cast a given stream to a standard IO stream. This cast can fail for memory streams as it requires the C fopencookie function to be available. This C function is not available on Windows. php://filterphp://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.
ExamplesExample #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
Example #5 php://memory and php://temp are not reusable php://memory and php://temp are not reusable, i.e. after the streams have been closed there is no way to refer to them again.
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