Why Can't You Get Process Title Using cli_get_process_title? Check if PHP Has Enabled the Related Extension

When writing command-line scripts in PHP, we may sometimes want to set or get the process title using cli_set_process_title and cli_get_process_title in order to better identify the current state of the running script, especially when monitoring processes with tools like ps, top, and others. This is very useful when developing CLI applications such as daemon processes or task queue consumers.

However, many developers encounter issues when calling cli_get_process_title(), such as receiving an empty string or false. Why does this happen, even though cli_set_process_title() was successfully called earlier to set the title? The problem may not lie in your code, but rather in how PHP was built.

Core Problem: Extension Not Enabled

The cli_set_process_title and cli_get_process_title functions are part of the proctitle support, which is an optional feature during PHP compilation. If your PHP doesn't have the --enable-cli option enabled and the --enable-proctitle option was not enabled during the build process, then these functions are effectively useless.

How to Confirm If proctitle Support Is Enabled?

You can check by running the following command:

php -i | grep "Process title"  

If there's no output or if you don't see the following line:

Process title support => enabled  

It means that your PHP environment doesn't have this feature enabled.

Example Code

Here’s an example of setting and attempting to get the process title:

<?php  
cli_set_process_title("my_worker_task");  
$title = cli_get_process_title();
<p>if ($title === false || $title === "") {<br>
echo "Unable to get process title, please check if proctitle support is enabled in PHP.\n";<br>
} else {<br>
echo "The current process title is: " . $title . "\n";<br>
}<br>

If your PHP doesn't have the relevant support enabled, you might only see a warning or an empty output when running this code.

Solution

1. Recompile PHP (Recommended for server deployment environments)

You need to recompile PHP with the --enable-cli (usually enabled by default) and --enable-proctitle options. For example:

./configure --enable-cli --enable-proctitle  
make && make install  

This will enable process title support, and after recompiling, you should be able to use both functions normally.

2. Use an Alternative Method (For Linux Systems)

If you can't recompile PHP, you can try manually setting the process title using exec() or calling a system command, like so:

<?php  
$title = "my_custom_task";  
exec("exec -a $title php your_script.php");  

However, note that this method is less elegant and may be unreliable if exec() is disabled or if system behavior differs across environments.

Conclusion

If cli_get_process_title() cannot retrieve the process title, it's likely not an issue with your code but rather with PHP not having the necessary support enabled. Developers encountering this problem should first check the build parameters of their PHP environment. This is especially important when using Docker or PHP versions bundled with certain operating systems.