chmod

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

    chmod — Changes file mode

    Description

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

    Attempts to change the mode of the specified file to that given in permissions.

    Parameters

    filename

    Path to the file.

    permissions

    Note that permissions is not automatically assumed to be an octal value, so to ensure the expected operation, you need to prefix permissions with a zero (0). Strings such as "g+w" will not work properly.

    <?php
    chmod    ("/somedir/somefile", 755); // decimal; probably incorrect
    chmod("/somedir/somefile", "u+rwx,go+rx"); // string; incorrect
    chmod("/somedir/somefile", 0755); // octal; correct value of mode
    ?>

    The permissions parameter consists of three octal number components specifying access restrictions for the owner, the user group in which the owner is in, and to everybody else in this order. One component can be computed by adding up the needed permissions for that target user base. Number 1 means that you grant execute rights, number 2 means that you make the file writeable, number 4 means that you make the file readable. Add up these numbers to specify needed rights. You can also read more about modes on Unix systems with 'man 1 chmod' and 'man 2 chmod'.

    <?php
    // Read and write for owner, nothing for everybody else
    chmod("/somedir/somefile", 0600);

    // Read and write for owner, read for everybody else
    chmod("/somedir/somefile", 0644);

    // Everything for owner, read and execute for others
    chmod("/somedir/somefile", 0755);

    // Everything for owner, read and execute for owner's group
    chmod("/somedir/somefile", 0750);
    ?>

    Return Values

    Returns true on success or false on failure.

    Errors/Exceptions

    Upon failure, an E_WARNING is emitted.

    Notes

    Note:

    The current user is the user under which PHP runs. It is probably not the same user you use for normal shell or FTP access. The mode can be changed only by user who owns the file on most systems.

    Note: This function will not work on remote files as the file to be examined must be accessible via the server's filesystem.

    See Also

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    User Contributed Notes 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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