## Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Filesystem and Streams Configuration Options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
allow_url_fopen | "1" | PHP_INI_SYSTEM |
allow_url_include | "0" | PHP_INI_SYSTEM | Available since PHP 5.2.0. Deprecated as of PHP 7.4.0.
user_agent | NULL | PHP_INI_ALL |
default_socket_timeout | "60" | PHP_INI_ALL |
from | "" | PHP_INI_ALL |
auto_detect_line_endings | "0" | PHP_INI_ALL |
sys_temp_dir | "" | PHP_INI_SYSTEM | Available since PHP 5.5.0.

Here's a short explanation of the configuration directives.

`allow_url_fopen` boolean

  This option enables the URL-aware fopen wrappers that enable accessing URL object like files. Default wrappers are provided for the access of remote files using the ftp or http protocol, some extensions like zlib may register additional wrappers.

`allow_url_include` boolean

  This option allows the use of URL-aware fopen wrappers with the following functions: include, include_once, require, require_once.

  > Note:

  > This setting requires allow_url_fopen to be on.

`user_agent` string

  Define the user agent for PHP to send.

`default_socket_timeout` integer

  Default timeout (in seconds) for socket based streams.

`from` string

  The email address to be used on unauthenticated FTP connections and as the value of From header for HTTP connections, when using the ftp and http wrappers, respectively.

`auto_detect_line_endings` boolean

  When turned on, PHP will examine the data read by fgets() and file() to see if it is using Unix, MS-Dos or Macintosh line-ending conventions.

  This enables PHP to interoperate with Macintosh systems, but defaults to Off, as there is a very small performance penalty when detecting the EOL conventions for the first line, and also because people using carriage-returns as item separators under Unix systems would experience non-backwards-compatible behaviour.

`sys_temp_dir` string