PHP fileinode Function
last modified April 3, 2025
The PHP fileinode function retrieves the inode number of a file.
Inodes are unique identifiers in Unix-like filesystems that store file metadata.
Basic Definition
The fileinode function returns the inode number of the specified
file. It takes one parameter: the filename as a string.
Syntax: fileinode(string $filename): int|false. Returns the inode
number or false on failure. Requires the file to exist and be accessible.
Basic fileinode Example
This shows the simplest usage of fileinode to get a file's inode.
<?php
declare(strict_types=1);
$filename = "example.txt";
$inode = fileinode($filename);
if ($inode !== false) {
echo "Inode number: " . $inode;
} else {
echo "Could not get inode number";
}
This retrieves and displays the inode number of "example.txt". The function returns false if the file doesn't exist or can't be accessed.
Checking File Identity
Inodes can be used to check if two paths refer to the same physical file.
<?php
declare(strict_types=1);
$file1 = "original.txt";
$file2 = "hardlink.txt";
$inode1 = fileinode($file1);
$inode2 = fileinode($file2);
if ($inode1 === $inode2) {
echo "Files are the same (hardlinked)";
} else {
echo "Files are different";
}
This compares inodes to determine if files are hardlinked. Files with the same inode share the same physical data on disk.
Directory Inode Example
fileinode works with directories as well as regular files.
<?php
declare(strict_types=1);
$dir = "/var/www";
$inode = fileinode($dir);
if ($inode !== false) {
echo "Directory inode: " . $inode;
} else {
echo "Could not get directory inode";
}
This gets the inode number of a directory. Directories in Unix-like systems are just special files with their own inodes.
Error Handling
Proper error handling is important when working with filesystem functions.
<?php
declare(strict_types=1);
$filename = "nonexistent.txt";
$inode = fileinode($filename);
if ($inode === false) {
echo "Error: File not found or permission denied";
// Additional error handling here
} else {
echo "Inode: " . $inode;
}
This demonstrates proper error checking. Always verify the return value isn't false before using the inode number.
Comparing Files
Inodes can help compare files without opening them.
<?php
declare(strict_types=1);
function areSameFile(string $file1, string $file2): bool {
$inode1 = fileinode($file1);
$inode2 = fileinode($file2);
return $inode1 !== false && $inode2 !== false && $inode1 === $inode2;
}
$result = areSameFile("file1.txt", "file2.txt");
echo $result ? "Same file" : "Different files";
This function uses inodes to check if two paths reference the same file. More reliable than comparing paths which might differ due to symlinks or hardlinks.
Best Practices
- Check Existence: Verify files exist before getting inodes.
- Error Handling: Always handle false return values.
- Cross-platform: Note inodes are Unix-specific.
- Caching: Results may be cached; use clearstatcache().
- Security: Validate paths when using user input.
Source
This tutorial covered the PHP fileinode function with practical
examples showing its usage in different scenarios.