readline_clear_history() clears in-memory readline input history. This guide explains the function with focused examples and the decisions that matter in real applications.
What Is readline_clear_history() in PHP?
Clears in-memory readline input history.
A typical call looks like this:
<?php
readline_clear_history();
The input arguments shown in the call identify the relevant connection, resource, value, path or configuration for the operation. Pay attention to argument order and to the return value demonstrated below.
Example 1: Basic Usage
This first example uses readline_clear_history() directly to demonstrate its basic purpose.
<?php
readline_add_history("temporary"); readline_clear_history();
The returned value illustrates clears in-memory readline input history. This does not automatically erase history already stored in a file.
Example 2: A Different Input or Option
The next example changes the input or option, showing another supported use of readline_clear_history().
<?php
readline_add_history("another command"); readline_clear_history(); print_r(readline_list_history());
The returned value illustrates clears in-memory readline input history. This does not automatically erase history already stored in a file.
Practical Example: Applying the Function
In application code, readline_clear_history() belongs in a controlled workflow with input validation, a checked result and cleanup where needed.
<?php
readline_add_history("secret command"); readline_clear_history(); echo count(readline_list_history());
The returned value illustrates clears in-memory readline input history. This does not automatically erase history already stored in a file.
Important Behavior and Edge Cases
- Main behavior: Clears in-memory readline input history.
- Important limitation: This does not automatically erase history already stored in a file.
- Requirements: This function uses the CLI readline extension; it is not designed for an ordinary web request.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
readline_clear_history() | Clears in-memory readline input history. |
readline_write_history | Writes readline history entries to a file. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
Ignoring the specific limits or preconditions of readline_clear_history(). | This does not automatically erase history already stored in a file. |
| Assuming every environment produces the same result. | This function uses the CLI readline extension; it is not designed for an ordinary web request. |
Key Takeaways
- Clears in-memory readline input history.
- This does not automatically erase history already stored in a file.
- This function uses the CLI readline extension; it is not designed for an ordinary web request.
Use readline_clear_history() when its behavior matches your task, and verify the relevant return value before taking further action. The output depends on the local configuration when it uses resources, files or an interactive terminal.