readline_read_history() loads readline history entries from a file. This guide explains the function with focused examples and the decisions that matter in real applications.
What Is readline_read_history() in PHP?
Loads readline history entries from a file.
A typical call looks like this:
<?php
readline_read_history([$filename]);
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_read_history() directly to demonstrate its basic purpose.
<?php
readline_read_history(sys_get_temp_dir() . "/shell-history.txt");
The returned value illustrates loads readline history entries from a file. Only load from a trusted path; imported history can contain sensitive commands.
Example 2: A Different Input or Option
The next example changes the input or option, showing another supported use of readline_read_history().
<?php
var_dump(readline_read_history("/tmp/known-history"));
The returned value illustrates loads readline history entries from a file. Only load from a trusted path; imported history can contain sensitive commands.
Practical Example: Applying the Function
In application code, readline_read_history() belongs in a controlled workflow with input validation, a checked result and cleanup where needed.
<?php
$historyFile = __DIR__ . "/cli-history.txt"; if (is_file($historyFile)) { readline_read_history($historyFile); print_r(readline_list_history()); }
The returned value illustrates loads readline history entries from a file. Only load from a trusted path; imported history can contain sensitive commands.
Important Behavior and Edge Cases
- Main behavior: Loads readline history entries from a file.
- Important limitation: Only load from a trusted path; imported history can contain sensitive commands.
- 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_read_history() | Loads readline history entries from a file. |
readline_write_history | Writes readline history entries to a file. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
Ignoring the specific limits or preconditions of readline_read_history(). | Only load from a trusted path; imported history can contain sensitive commands. |
| 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
- Loads readline history entries from a file.
- Only load from a trusted path; imported history can contain sensitive commands.
- This function uses the CLI readline extension; it is not designed for an ordinary web request.
Use readline_read_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.