PHP: Hypertext Preprocessor (original) (raw)

chmod

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

chmod — Changes file mode

Description

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](reserved.constants.php#constant.true) on success or [false](reserved.constants.php#constant.false) on failure.

Errors/Exceptions

Upon failure, an [E_WARNING](errorfunc.constants.php#constant.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 onremote files as the file to be examined must be accessible via the server's filesystem.

Found A Problem?

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));

Geoff W ¶

15 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

masha at mail dot ru ¶

19 years ago

chris at ocproducts dot com ¶

5 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.

alex at feidesign dot com ¶

20 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.

sander ¶