fileowner() Function is one of the PHP operations used in filesystem and stream workflows. Returns the numeric user owner identifier of a file. The examples below show what it does and how to handle its result.
What Is fileowner() Function?
Returns the numeric user owner identifier of a file.
Its syntax is:
fileowner(string $filename)
The parameters are:
string $filename— The source or destination filesystem path.
Return value: The declared return type is int|false. User IDs differ across hosts and may be unavailable on some platforms.
Important: User IDs differ across hosts and may be unavailable on some platforms.
Example 1: Basic Usage
The basic example focuses on the behavior of fileowner() Function: returns the numeric user owner identifier of a file. Inputs are defined locally or shown as application-controlled paths.
<?php
$ownerIdentifier = fileowner(__FILE__);
if ($ownerIdentifier !== false) { echo $ownerIdentifier; }
The displayed value, file content or return status depends on the input and surrounding environment. Results involving local paths, identifiers or generated files are not fixed values.
Example 2: A Different Use Case
This second example illustrates another input or execution condition for fileowner() Function. Notice the different checks, arguments, or output handling.
<?php
$ownerIdentifier = @fileowner(__DIR__ . "/missing.txt");
var_dump($ownerIdentifier === false);
This variation matters because user IDs differ across hosts and may be unavailable on some platforms.
Practical Example: Using the Operation in an Application
The following example demonstrates how fileowner() Function fits into a more complete file or archive workflow, including inputs and appropriate checks.
<?php
$identifier = fileowner(__FILE__);
if ($identifier !== false) { echo "File UID: " . $identifier; }
The operation shown is an illustrative script. Adapt the filenames, required permissions, and error handling to your own controlled application environment before running it.
Important Behavior and Edge Cases
- Function behavior: Returns the numeric user owner identifier of a file.
- Limitation: User IDs differ across hosts and may be unavailable on some platforms.
Comparison With Related Functions
| Function or Method | Difference |
|---|---|
fileowner() Function | Returns the numeric user owner identifier of a file. |
filegroup() | Returns the group ID rather than the owner user ID. |
Use fileowner() Function for the specific behavior described above. The related operation, filegroup(), serves a different purpose; do not substitute it unless that different behavior is intended.
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Assuming filesystem metadata is always available and current. | User IDs differ across hosts and may be unavailable on some platforms. Check failure returns and refresh stat information when files may have changed. |
| Treating filegroup() as an interchangeable replacement for fileowner() Function. | Returns the group ID rather than the owner user ID. |
Key Takeaways
- Returns the numeric user owner identifier of a file.
- User IDs differ across hosts and may be unavailable on some platforms.
- Related operation: filegroup() — Returns the group ID rather than the owner user ID.
fileowner() Function is useful when its specific behavior matches your application requirement. Keep paths controlled, check failures, and handle environment-dependent operations deliberately.