How Can I Achieve Live Output from PHP Shell Commands?

Live Output with PHP Using popen() and passthru()

PHP's shell_exec() function allows you to execute a command and capture its output. However, displaying the output live during command execution is not possible with shell_exec() or other built-in functions like system(), exec(), or passthru().

For live output, consider using popen() instead. It opens a pipe to a process and allows you to read or write its input/output as if it were a file.

Passthru() for Immediate Output:

If you need to display the output directly to the user without waiting for command completion, you can use passthru():

echo '<pre class="brush:php;toolbar:false">';
passthru($cmd);
echo '

';

Popen() for Real-Time Output:

To display the output live as the command executes, use popen() and a while loop:

while (@ ob_end_flush()); // end output buffers

$proc = popen($cmd, 'r');
echo '<pre class="brush:php;toolbar:false">';
while (!feof($proc)) {
    echo fread($proc, 4096);
    @ flush();
}
echo '

';

This code opens a pipe to the command, reads its output in chunks, and displays it on the fly.

Useful Information:

• Call session_write_close() before the loop to prevent session issues.
• For servers behind nginx, add the header 'X-Accel-Buffering: no' to prevent nginx buffering.
• Note that live output may be disruptive if your code is running in a loop that also updates the session.

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