How to Check if a File Exists with file_exists()

Table Of Contents

• The Fix
• Why This Works

The Fix

<?php

// Basic file existence check
if (file_exists('/path/to/file.txt')) {
    echo "File exists!";
    $content = file_get_contents('/path/to/file.txt');
} else {
    echo "File not found";
}

// Check before writing to avoid overwriting
$filename = 'important-data.json';
if (file_exists($filename)) {
    // Create backup before overwriting
    copy($filename, $filename . '.backup');
}
file_put_contents($filename, json_encode($data));

// Safer file operations with existence check
function safeFileRead(string $filepath): string|null {
    if (!file_exists($filepath)) {
        return null;
    }
    
    if (!is_readable($filepath)) {
        throw new RuntimeException("File exists but is not readable: $filepath");
    }
    
    return file_get_contents($filepath);
}

// Check multiple files
$requiredFiles = ['config.php', 'database.php', 'routes.php'];
$missingFiles = [];

foreach ($requiredFiles as $file) {
    if (!file_exists($file)) {
        $missingFiles[] = $file;
    }
}

if (!empty($missingFiles)) {
    die("Missing required files: " . implode(', ', $missingFiles));
}

// File vs Directory distinction
$path = '/some/path';
if (file_exists($path)) {
    if (is_file($path)) {
        echo "It's a file";
        echo "Size: " . filesize($path) . " bytes";
    } elseif (is_dir($path)) {
        echo "It's a directory";
        echo "Contents: " . count(scandir($path)) - 2 . " items";
    }
}

// Configuration file loading pattern
function loadConfig(string $configFile = 'config.php'): array {
    $defaultConfig = [
        'debug' => false,
        'database' => 'localhost'
    ];
    
    if (!file_exists($configFile)) {
        return $defaultConfig;
    }
    
    $userConfig = include $configFile;
    return array_merge($defaultConfig, $userConfig);
}

// File age check combined with existence
function isFileExpired(string $filepath, int $maxAgeHours = 24): bool {
    if (!file_exists($filepath)) {
        return true; // Consider non-existent files as expired
    }
    
    $fileAge = time() - filemtime($filepath);
    return $fileAge > ($maxAgeHours * 3600);
}

// Usage examples
$config = loadConfig(); // Uses default if config.php doesn't exist

if (isFileExpired('cache/data.json', 2)) {
    // Regenerate cache if file is missing or older than 2 hours
    generateCache();
}

Why This Works

file_exists() is essential for robust file handling:

1. Prevents Errors: Avoid "file not found" fatal errors
2. Conditional Logic: Different behavior based on file presence
3. Universal Check: Works for files, directories, and symlinks
4. Performance: Fast check before expensive file operations

Important Notes:

• Returns true for files, directories, and symlinks
• Use is_file() to check specifically for files
• Use is_dir() to check specifically for directories
• Combine with is_readable() for permission checks

Always check file existence before reading, and consider what should happen when files are missing.