chmod

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

    chmod — 改变文件模式

    说明

    chmod(string $filename, int $permissions): bool

    尝试将 filename 所指定文件的模式改成 permissions 所给定的。

    参数

    filename

    文件的路径。

    permissions

    注意 permissions 不会被自动当成八进制数值，因此为确保正确操作，需要给 permissions 前面加上 0。诸如“g+w”之类的字符串将无法正常工作。

    <?php
    chmod    ("/somedir/somefile", 755); // 十进制数，可能不对
    chmod("/somedir/somefile", "u+rwx,go+rx"); // 字符串，不对
    chmod("/somedir/somefile", 0755); // 八进制数，正确的 mode 值
    ?>

    permissions 参数包含三个八进制数按顺序分别指定了所有者、所有者所在的组以及所有人的访问限制。每一部分都可以通过加入所需的权限来计算出所要的权限。数字 1 表示使文件可执行，数字 2 表示使文件可写，数字 4 表示使文件可读。加入这些数字来制定所需要的权限。有关 UNIX 系统的文件权限可以阅读手册“man 1 chmod”和“man 2 chmod”。

    <?php
    // 所有者可以读写，其他人什么也不能做
    chmod("/somedir/somefile", 0600);

    // 所有者可以读写，其他人可以读
    chmod("/somedir/somefile", 0644);

    // 所有者可以读写执行，其他人可以读和执行
    chmod("/somedir/somefile", 0755);

    // 所有者可以读写执行，所有者同组可以读和执行
    chmod("/somedir/somefile", 0750);
    ?>

    返回值

    成功时返回 true， 或者在失败时返回 false。

    错误／异常

    失败时会发出 E_WARNING。

    注释

    注意:

    当前用户指的是执行 PHP 的用户。很可能和通常访问 shell 或者 FTP 的用户不是同一个。在大多数系统下文件模式只能被拥有该文件的用户改变。

    注意: 此函数不能作用于远程文件，被检查的文件必须是可通过服务器的文件系统访问的。

    参见

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    用户贡献的备注 6 notes

    up
    58
    MethodicalFool
    14 years ago
    BEWARE, a couple of the examples in the comments suggest doing something like this:

    chmod(file_or_dir_name, intval($mode, 8));

    However, if $mode is an integer then intval( ) won't modify it. So, this code...

    $mode = 644;
    chmod('/tmp/test', intval($mode, 8));

    ...produces permissions that look like this:

    1--w----r-T

    Instead, use octdec( ), like this:

    chmod(file_or_dir_name, octdec($mode));

    See also: http://www.php.net/manual/en/function.octdec.php
    up
    38
    Geoff W
    14 years ago
    BEWARE using quotes around the second parameter...

    If you use quotes eg

    chmod (file, "0644");

    php will not complain but will do an implicit conversion to an int before running chmod. Unfortunately the implicit conversion doesn't take into account the octal string so you end up with an integer version 644, which is 1204 octal
    up
    36
    masha at mail dot ru
    19 years ago
    Usefull reference:

    Value Permission Level
    400 Owner Read
    200 Owner Write
    100 Owner Execute
    40 Group Read
    20 Group Write
    10 Group Execute
    4 Global Read
    2 Global Write
    1 Global Execute

    (taken from http://www.onlamp.com/pub/a/php/2003/02/06/php_foundations.html)
    up
    8
    chris at ocproducts dot com
    4 years ago
    Windows has a very different file permission model to Unix and integrates them only minimally.

    On Windows, all this function can do is to change the "read only" flag, which is turned on if $mode & 0200 does not pass.
    i.e. it only checks if u+w is missing from the bitmask, and if it is, it sets the read only flag.

    The executable flag cannot be set as Windows determines it based on file extension.
    The write flag cannot be set as Windows determines write access based on ACLs, which are not integrated here.
    up
    6
    alex at feidesign dot com
    19 years ago
    If you cannot chmod files/directories with PHP because of safe_mode restrictions, but you can use FTP to chmod them, simply use PHP's FTP-functions (eg. ftp_chmod or ftp_site) instead. Not as efficient, but works.
    up
    2
    sander
    15 years ago
    if you want to chmod directories too, use this

    <?php
    $iterator     = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($pathname), RecursiveIteratorIterator::SELF_FIRST);

    foreach(    $iterator as $item) {
    chmod($item, $filemode);
    }
    ?>
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