运行时配置

这些函数的行为受 php.ini 中的设置影响。

文件系统和流配置选项
名字 默认 可修改范围 更新日志
allow_url_fopen "1" PHP_INI_SYSTEM 在 PHP <= 4.3.4 时是 PHP_INI_ALL。PHP 4.0.4 版以后可用。
user_agent NULL PHP_INI_ALL PHP 4.3.0 版以后可用。
default_socket_timeout "60" PHP_INI_ALL PHP 4.3.0 版以后可用。
from "" PHP_INI_ALL  
auto_detect_line_endings "0" PHP_INI_ALL PHP 4.3.0 版以后可用。

这是配置指令的简短说明。

allow_url_fopen boolean

本选项激活了 URL 形式的 fopen 封装协议使得可以访问 URL 对象例如文件。默认的封装协议提供用 ftp 和 http 协议来访问远程文件，一些扩展库例如 zlib 可能会注册更多的封装协议。

Note:

出于安全性考虑，此选项只能在 php.ini 中设置。

Note:

此选项是紧接着版本 4.0.3 发布后引进的。版本 4.0.3 以及之前的版本只能在编译时通过配置项 --disable-url-fopen-wrapper 来取消此特性。

Warning

Windows 版在 PHP 4.3.0 之前，以下函数不支持远程文件访问：include，include_once, require，require_once 和GD 和图像处理 函数中的 imagecreatefromXXX 函数。

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

定义 PHP 发送的 User-Agent。

default_socket_timeout integer

基于 socket 的流的默认超时时间（秒）。

Note: 本配置参数是 PHP 4.3.0 引进的。

from string

定义匿名 ftp 的密码（email 地址）。

auto_detect_line_endings boolean

当设为 On 时，PHP 将检查通过 fgets() 和 file() 取得的数据中的行结束符号是符合 Unix，MS-DOS，还是 Macintosh 的习惯。

这使得 PHP 可以和 Macintosh 系统交互操作，但是默认值是 Off，因为在检测第一行的 EOL 习惯时会有很小的性能损失，而且在 Unix 系统下使用回车符号作为项目分隔符的人们会遭遇向下不兼容的行为。

Note: 本配置参数是 PHP 4.3.0 引进的。

User Contributed Notes

Chris 27-Feb-2017 05:14
If you want to use auto_detect_line_endings, e.g. to recognize carriage return on a Classic Mac file, you must set it before calling fopen. You can then reset it to its original value. E.g,

$original = ini_get("auto_detect_line_endings");
ini_set("auto_detect_line_endings", true);
$handle = fopen($someFile, "r");
ini_set("auto_detect_line_endings", $original);
while (($line = fgets($handle)) !== false) {
  echo "$line\n"; // etc
}

(Reference: https://bugs.php.net/bug.php?id=63341&edit=2)

Keep in mind also that Mac OS X bash does not handle carriage returns well, so if it seems like your code is not working when testing from the command line, redirect your output to a file and then try looking at that. On my system, doing it directly on the command line only showed the last line (with or without this setting turned on).

Also note that this will not do what you want if you have a file with mixed line endings (!). If you really care about that case, you have to do something else, like run the file through a translation first and then read it.
traian dot bratucu at gmail dot com 14-Feb-2017 08:16
Please note that although you may try to set default_socket_timeout to something over 20s, you may get tricked by the Linux kernel.

The default value of tcp_syn_retries is set to 5, which will effectively timeout any TCP connection after roughly 20s, no matter what limits you set in PHP higher than this.

The value can be altered by root only, like this:

 echo 6 > /proc/sys/net/ipv4/tcp_syn_retries

A value of 6, as above, will give you a timeout up to ~45s.
Pistachio 31-Jan-2012 09:53
I'm surprised this isn't mentioned in docs here, but to set these values at runtime use "ini_set()". For example:

<?php
ini_set("auto_detect_line_endings", true);

// Now I can invoke fgets() on files that contain silly \r line endings.
?>