PHP fstat Function

last modified April 3, 2025

The PHP fstat function retrieves file status information from an open file pointer. It provides details like size, permissions, and timestamps.

Basic Definition

The fstat function returns an array with statistics about a file. It requires an open file resource handle as its only parameter.

Syntax: fstat(resource $stream): array|false. The function returns an associative array on success or false on failure.

Basic fstat Example

This example shows how to get basic file information using fstat.

basic_fstat.php

<?php

declare(strict_types=1);

$file = fopen(’example.txt’, ‘r’); $stats = fstat($file);

print_r($stats); fclose($file);

This opens a file and prints its statistics. The output includes file size, access time, and other metadata. Always close files after use.

Getting File Size

This example demonstrates extracting the file size from fstat results.

file_size.php

<?php

declare(strict_types=1);

$file = fopen(’example.txt’, ‘r’); $stats = fstat($file);

if ($stats !== false) { echo “File size: " . $stats[‘size’] . " bytes”; } fclose($file);

The ‘size’ index contains the file size in bytes. We check if fstat succeeded before accessing the array. This is good practice for error handling.

Checking File Modification Time

This example shows how to get the last modification time of a file.

modification_time.php

<?php

declare(strict_types=1);

$file = fopen(’example.txt’, ‘r’); $stats = fstat($file);

if ($stats !== false) { $mtime = date(‘Y-m-d H:i:s’, $stats[‘mtime’]); echo “Last modified: " . $mtime; } fclose($file);

The ‘mtime’ index contains the Unix timestamp of last modification. We format it for human readability using date(). This helps in file monitoring systems.

File Permissions Example

This example demonstrates checking file permissions using fstat.

file_permissions.php

<?php

declare(strict_types=1);

$file = fopen(’example.txt’, ‘r’); $stats = fstat($file);

if ($stats !== false) { $permissions = decoct($stats[‘mode’] & 0777); echo “File permissions: " . $permissions; } fclose($file);

The ‘mode’ index contains file permissions in octal format. We mask it with 0777 to get only permission bits. decoct() converts it to readable octal.

Comparing File Stats

This example compares stats of two files to check if they’re identical.

compare_files.php

<?php

declare(strict_types=1);

$file1 = fopen(‘file1.txt’, ‘r’); $file2 = fopen(‘file2.txt’, ‘r’);

$stats1 = fstat($file1); $stats2 = fstat($file2);

if ($stats1[‘ino’] === $stats2[‘ino’]) { echo “Files are the same (same inode)”; } else { echo “Files are different”; }

fclose($file1); fclose($file2);

The ‘ino’ index contains the inode number, unique per file. Comparing inodes is more reliable than comparing filenames. This helps detect hard links.

Best Practices

• Error Handling: Always check if fstat returns false.

• Resource Management: Close files after getting stats.

• Performance: Cache results if needed multiple times.

• Security: Validate file paths before opening.

Source

PHP fstat Documentation

This tutorial covered the PHP fstat function with practical examples showing its usage for file information retrieval.

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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