PHP fileperms Function

last modified April 3, 2025

The PHP fileperms function retrieves permissions for a file or directory. It returns the permissions as a numeric value that can be formatted.

Basic Definition

The fileperms function returns the permissions of the specified file. The return value is a bitmask that needs decoding to human-readable form.

Syntax: fileperms(string $filename): int|false. Returns false on failure. The result contains file type and permission bits combined.

Basic fileperms Example

This shows the simplest usage of fileperms to get permissions.

basic_fileperms.php

<?php

declare(strict_types=1);

$filename = "example.txt";
$perms = fileperms($filename);

echo $perms; // Outputs numeric value like 33206

This returns a numeric value representing the file permissions. The number needs to be converted to octal for meaningful interpretation.

Formatting Permissions

We can format the numeric permissions to a human-readable string.

format_perms.php

<?php

declare(strict_types=1);

$filename = "example.txt";
$perms = fileperms($filename);

echo substr(sprintf('%o', $perms), -4); // Outputs like 0644

This converts the permissions to octal and shows the last 4 digits. The first digit represents special bits, the next three are owner/group/others.

Checking Specific Permissions

We can check if specific permissions are set using bitwise operations.

check_perms.php

<?php

declare(strict_types=1);

$filename = "example.txt";
$perms = fileperms($filename);

if ($perms & 0x0080) {
    echo "Owner has write permission\n";
} else {
    echo "Owner doesn't have write permission\n";
}

This checks if the owner has write permission (0x0080). Bitwise AND compares the permission bits with our test value.

Getting File Type

The permission value also contains information about the file type.

file_type.php

<?php

declare(strict_types=1);

$filename = "example.txt";
$perms = fileperms($filename);

switch ($perms & 0xF000) {
    case 0xC000: echo "Socket"; break;
    case 0xA000: echo "Symbolic link"; break;
    case 0x8000: echo "Regular file"; break;
    case 0x6000: echo "Block device"; break;
    case 0x4000: echo "Directory"; break;
    case 0x2000: echo "Character device"; break;
    case 0x1000: echo "FIFO pipe"; break;
    default: echo "Unknown file type";
}

This checks the high bits of the permission value to determine file type. Each file type has a unique identifier in the highest bits.

Complete Permission String

We can create a complete permission string like "drwxr-xr-x".

full_perms.php

<?php

declare(strict_types=1);

function getPerms($filename): string {
    $perms = fileperms($filename);
    $info = '';
    
    $info .= (($perms & 0x4000) ? 'd' : '-');
    $info .= (($perms & 0x0100) ? 'r' : '-');
    $info .= (($perms & 0x0080) ? 'w' : '-');
    $info .= (($perms & 0x0040) ? 'x' : '-');
    $info .= (($perms & 0x0020) ? 'r' : '-');
    $info .= (($perms & 0x0010) ? 'w' : '-');
    $info .= (($perms & 0x0008) ? 'x' : '-');
    $info .= (($perms & 0x0004) ? 'r' : '-');
    $info .= (($perms & 0x0002) ? 'w' : '-');
    $info .= (($perms & 0x0001) ? 'x' : '-');
    
    return $info;
}

echo getPerms("example.txt"); // Outputs like -rw-r--r--

This builds a complete permission string by checking each permission bit. The first character shows file type, followed by owner/group/others permissions.

Best Practices

Error Handling: Always check if fileperms returns false.
Security: Be careful with sensitive file permissions.
Cross-platform: Results may vary between operating systems.
Performance: Cache results if checking repeatedly.

Source

PHP fileperms Documentation

This tutorial covered the PHP fileperms function with practical examples showing how to check and interpret file permissions.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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