Backend Development 3 min read

Using PHP chmod() to Set File Permissions

This article explains how to use PHP's chmod() function to change file permissions, describes permission masks, provides the syntax and a practical example that sets a file's mode to 644, and includes the full PHP code snippet.

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Using PHP chmod() to Set File Permissions

In PHP, you can use the chmod() function to set a file's permissions. The chmod() function accepts two parameters: the first is the file path, and the second is the permission mask expressed in octal.

The permission mask is a three‑digit number that represents the owner, group, and others permissions. Each digit corresponds to read (4), write (2), and execute (1). For example, the mask 755 gives the owner read, write, and execute permissions, the group read and execute, and others execute only.

To use the chmod() function to set file permissions, the syntax is:

chmod($filename, $permissions);

Where:

$filename is the path of the file whose permissions you want to set.

$permissions is the permission mask expressed in octal.

Practical Example:

The following example shows how to use chmod() to set the permissions of the file myfile.txt to 644 (owner read/write, group and others read only):

<?php

// Path of the file to set permissions
$filename = 'myfile.txt';

// Permission mask in octal form
$permissions = 0644;

// Use chmod() to set the file permissions
chmod($filename, $permissions);

?>

After executing this script, the file myfile.txt will have its permissions set to 644.

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