The compatibility of proc_terminate function for Windows and Linux systems

In PHP, the proc_terminate function is used to terminate a process opened by proc_open . Due to the differences in the underlying process management mechanism of the operating system, there are also differences in the performance of proc_terminate on Windows and Linux systems. This article will analyze the compatibility of this function in detail in these two environments to help developers understand and use it correctly.

1. Introduction to proc_terminate function

The definition of proc_terminate is as follows:

 bool proc_terminate ( resource $process [, int $signal = 15 ] )

• $process : Process resource obtained through proc_open .

• $signal : The signal sent to the process, the default is 15 (SIGTERM, elegant termination signal).

The function returns true to send the signal successfully, and false to fail.

2. Performance on Windows

The process model of Windows system is different from Linux:

• Windows does not have a Linux-like Unix signaling mechanism.

• proc_terminate actually forces the process to end via the TerminateProcess API on Windows.

• The signal parameter is usually ignored on Windows, and all signals are treated as forced termination.

Sample code:

 <?php
$process = proc_open('ping -n 10 127.0.0.1', [
    1 => ['pipe', 'w'],
    2 => ['pipe', 'w'],
], $pipes);

sleep(2);

proc_terminate($process);  // The signal parameters here are invalid，Forced termination directly
proc_close($process);
?>

On Windows, calling proc_terminate is basically equivalent to forcing a process to kill, and does not support sending custom signals or elegant shutdowns.

3. Performance on Linux system

Linux system supports Unix signals, and the $signal parameter of proc_terminate is very important:

• The default signal SIGTERM (15) requests the process exits normally.

• The process can be forced to be killed by changing the signal to SIGKILL (9).

• Allow users to send other signals (such as SIGINT , SIGHUP , etc.) as needed.

Sample code:

 <?php
$process = proc_open('sleep 30', [
    1 => ['pipe', 'w'],
    2 => ['pipe', 'w'],
], $pipes);

sleep(2);

proc_terminate($process, SIGTERM);  // Elegant termination
// If the process does not respond，You can try to force termination
// proc_terminate($process, SIGKILL);

proc_close($process);
?>

On Linux, proc_terminate provides more flexible control, allowing developers to send specific signals to implement different process termination strategies.

4. Compatibility summary

Developers should pay attention to these differences when developing cross-platform to avoid relying on signal parameters to take effect on Windows.

5. Conclusion

There are significant differences in the performance of proc_terminate on Windows and Linux systems. Windows systems do not support Unix signaling mechanisms, and all termination operations are forced to end, while Linux systems support sending multiple signals to achieve more detailed process management. Understanding this is essential for writing cross-platform PHP process management code.