PHP - Manual: readlink

2024-12-21

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readlink

(PHP 4, PHP 5, PHP 7, PHP 8)

readlink — 返回符号连接指向的目标

说明

readlink(string $path): string

readlink() 和同名的 C 函数做同样的事，返回符号连接的内容。

参数

path: 链接符号的路径。

更新日志

版本	说明
5.3.0	此函数在 Windows 平台下可用（Vista、Server 2008 或更高版本）。

返回值

返回链接的路径内容，出错则返回 false。

范例

示例 #1 readlink() 例


<?php

// output e.g. /boot/vmlinux-2.4.20-xfs
echo readlink('/vmlinuz');

?>

参见

is_link() - 判断给定文件名是否为一个符号连接
symlink() - 建立符号连接
linkinfo() - 获取一个连接的信息

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User Contributed Notes 4 notes

down

MarkAndrewSlade at gmail dot com ¶

13 years ago


This will trigger a warning and return false if you pass it a non-symlink.  If the file doesn't exist, it will trigger a differently worded warning.

mslade@jupiter ~$ touch a
mslade@jupiter ~$ ln -s a b
mslade@jupiter ~$ ls -l {a,b}
-rw------- 1 mslade mslade 0 2009-06-10 15:27 a
lrwxrwxrwx 1 mslade mslade 1 2009-06-10 15:27 b -> a
mslade@jupiter ~$ php -r "var_dump(readlink('b'));"
string(1) "a"
mslade@jupiter ~$ php -r "var_dump(readlink('a'));"

Warning: readlink(): Invalid argument in Command line code on line 1
bool(false)
mslade@jupiter ~$ php -r "var_dump(readlink('c'));"

Warning: readlink(): No such file or directory in Command line code on line 1
bool(false)

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casinero dot triste at OH_NO_SPAM dot gmail dot com ¶

4 years ago


A little function to readlink TO THE END:
(realpath can't do this if the symlink (ultimately) points to a non-existing path, since it just returns false in this case.)

function readlinkToEnd($linkFilename) {
  if(!is_link($linkFilename)) return $linkFilename;
  $final = $linkFilename;
  while(true) {
    $target = readlink($final);
    if(substr($target, 0, 1)=='/') $final = $target;
    else $final = dirname($final).'/'.$target;
    if(substr($final, 0, 2)=='./') $final = substr($final, 2);
    if(!is_link($final)) return $final;
  }
}

down

-1

casinero dot triste at OH_NO_SPAM dot gmail dot com ¶

4 years ago


A little function to readlink TO THE END:
(realpath can't do this if the symlink (ultimately) points to a non-existing path, since it just returns false in this case.)

function readlinkToEnd($linkFilename) {
  if(!is_link($linkFilename)) return $linkFilename;
  $final = $linkFilename;
  while(true) {
    $target = readlink($final);
    if(substr($target, 0, 1)=='/') $final = $target;
    else $final = dirname($final).'/'.$target;
    if(substr($final, 0, 2)=='./') $final = substr($final, 2);
    if(!is_link($final)) return $final;
  }
}

down

-6

ayon at hyurl dot com ¶

5 years ago


It is neccesary to be notified that readlink only works for a real link file, if this link file locates to a directory, you cannot detect and read its contents, the is_link() function will always return false and readlink() will display a warning is you try to do. Like the following codes:
<?php
//assume that A is a directory located in C:, B is a symlink to A, and A contents a file named C.
echo is_link('B/C'); //false
echo readlink('B/C'); //false and a warning will be displayed
//instead, you should use realpath() function to get the real path of C
echo realpath('B/C'); //C:\A\C
?>

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官方地址：https://www.php.net/manual/en/function.readlink.php

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readlink

说明

参数

更新日志

返回值

范例

参见

User Contributed Notes 4 notes