Allows execution of PHP included directly on the command line. The PHP start and end tags (<?php and ?>) are not needed and will cause a parse error if present.

Note:

Care must be taken when using this form of PHP not to collide with command line variable substitution done by the shell.

Example #2 Getting a syntax error when using double quotes

$ php -r "$foo = get_defined_constants();"
PHP Parse error:  syntax error, unexpected '=' in Command line code on line 1

Parse error: syntax error, unexpected '=' in Command line code on line 1

The problem here is that sh/bash performs variable substitution even when using double quotes ". Since the variable $foo is unlikely to be defined, it expands to nothing which results in the code passed to PHP for execution actually reading:

$ php -r " = get_defined_constants();"

The correct way would be to use single quotes '. Variables in single-quoted strings are not expanded by sh/bash.

Example #3 Using single quotes to prevent the shell's variable substitution

$ php -r '$foo = get_defined_constants(); var_dump($foo);'
array(370) {
  ["E_ERROR"]=>
  int(1)
  ["E_WARNING"]=>
  int(2)
  ["E_PARSE"]=>
  int(4)
  ["E_NOTICE"]=>
  int(8)
  ["E_CORE_ERROR"]=>
  [...]

If using a shell other than sh/bash, further issues might be experienced - if appropriate, a bug report should be opened at » http://bugs.php.net/. It is still easy to run into trouble when trying to use variables (shell or PHP) in commnad-line code, or using backslashes for escaping, so take great care when doing so. You have been warned!

Note:

-r is available in the CLI SAPI, but not in the CGI SAPI.

Note:

This option is only intended for very basic code, so some configuration directives (such as auto_prepend_file and auto_append_file) are ignored in this mode.