PHP touch() updates a file modification/access time, creating the file if needed. The examples below show how the call behaves, where it is useful, and which limitations matter.
What Is touch() in PHP?
Updates a file modification/access time, creating the file if needed.
Its call structure is:
touch($filename, [$mtime], [$atime])The arguments identify the values or resources passed to touch(). Read the examples with attention to the type of each supplied argument and to whether the function modifies its input or returns a separate result.
Example 1: Basic Usage
This example introduces touch with a direct call and a small, readable input.
<?php
touch($filePath);Updates a file modification/access time, creating the file if needed. A failed operation often indicates missing permissions or an invalid destination.
Example 2: Another Behavior or Input
Compare this input with the previous example: changing the data or option can affect how touch behaves.
<?php
touch($filePath, strtotime("2026-01-01 UTC"));The changed input illustrates why output may differ with the chosen values or environment. A failed operation often indicates missing permissions or an invalid destination.
Practical Example: Using the Feature
The following example incorporates touch into a workflow. Values such as paths, connection handles and configuration options must come from trusted application settings.
<?php
$filePath = sys_get_temp_dir() . "/test-marker-" . bin2hex(random_bytes(3)); if (touch($filePath)) { echo "Updated"; unlink($filePath); }In a real application, check each operation result, validate values before use and clean up acquired resources. A failed operation often indicates missing permissions or an invalid destination.
Important Behavior and Edge Cases
- Purpose: Updates a file modification/access time, creating the file if needed.
- Key limitation: A failed operation often indicates missing permissions or an invalid destination.
- Failure handling: Check return values and handle invalid inputs and unavailable operating-system or extension features where relevant.
Comparison With Related Functions
| Function or Approach | Best Fit |
|---|---|
touch() | Updates a file modification/access time, creating the file if needed. |
filemtime() | Reads a file modification timestamp; touch() can change it. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| A failed operation often indicates missing permissions or an invalid destination. | The correct approach depends on this behavior: A failed operation often indicates missing permissions or an invalid destination. |
| Ignoring errors or cleanup after the operation. | Validate inputs and check each result; close files, restore settings or release resources when the operation requires it. |
Key Takeaways
- Updates a file modification/access time, creating the file if needed.
- A failed operation often indicates missing permissions or an invalid destination.
- Use the examples as starting points, and adapt environmental paths, resources and permissions rather than assuming fixed results.
touch is useful when its specific behavior fits the problem. The safest implementations combine the correct API with input validation, error checking and resource cleanup.