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|false

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。

返回值

返回链接的路径内容，出错则返回 false。

注意: 如果 path 不是符号链接，则该函数将失败，但在 Windows 上除外，其中将返回规范化的路径。

示例

示例 #1 readlink() 示例

<?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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用户贡献的备注 3 notes

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MarkAndrewSlade at gmail dot com ¶

15 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)

down

casinero dot triste at OH_NO_SPAM dot gmail dot com ¶

7 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 ¶

7 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;
  }
}