PHP realpath Function

last modified April 3, 2025

The PHP realpath function resolves absolute canonical paths from relative or symbolic paths. It expands all symbolic links and resolves path components.

Basic Definition

The realpath function returns the absolute canonicalized pathname. It resolves all symbolic links, '/./', '/../' and extra '/' characters.

Syntax: realpath(string $path): string|false. Returns the absolute path on success or false on failure. The function is binary-safe.

Basic realpath Example

This shows the simplest usage of realpath to resolve a relative path.

basic_realpath.php

<?php

declare(strict_types=1);

$path = "../config/settings.ini";
$absolute = realpath($path);

echo $absolute; // Outputs absolute path like: /home/user/project/config/settings.ini

This converts a relative path to an absolute one. The exact output depends on your filesystem structure. The function returns false if the path doesn't exist.

Resolving Symbolic Links

realpath resolves symbolic links to their actual paths.

symlink_resolution.php

<?php

declare(strict_types=1);

// Assuming /var/www is a symlink to /srv/www
$path = "/var/www/html/index.php";
$absolute = realpath($path);

echo $absolute; // Outputs: /srv/www/html/index.php

Here the function resolves the symbolic link to the actual path. This is useful for getting the true location of files behind symlinks.

Handling Non-Existent Paths

realpath returns false when the path doesn't exist.

nonexistent_path.php

<?php

declare(strict_types=1);

$path = "/nonexistent/path/to/file.txt";
$absolute = realpath($path);

var_dump($absolute); // Outputs: bool(false)

Always check the return value before using it. This prevents errors when working with paths that might not exist in your filesystem.

Resolving Relative Components

The function resolves relative path components like '../' and './'.

relative_components.php

<?php

declare(strict_types=1);

$path = "/var/www/../tmp/./file.log";
$absolute = realpath($path);

echo $absolute; // Outputs: /tmp/file.log

This resolves '/var/www/../tmp' to '/tmp' and './file.log' to 'file.log'. The result is the simplest absolute path representation.

Windows Path Example

realpath works with Windows paths using backslashes.

windows_path.php

<?php

declare(strict_types=1);

$path = "C:\\Windows\\System32\\..\\notepad.exe";
$absolute = realpath($path);

echo $absolute; // Outputs: C:\Windows\notepad.exe

The function correctly handles Windows-style paths and resolves the parent directory reference. It works with both forward and backward slashes.

Best Practices

Error Checking: Always check if the return value is false.
Security: Use for path validation before file operations.
Performance: Cache results when used frequently.
Cross-platform: Works consistently across operating systems.

Source

PHP realpath Documentation

This tutorial covered the PHP realpath function with practical examples showing its usage in different scenarios.

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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