How to Capture and Handle StdErr Output After Using PHP\'s exec()?

How to Access StdErr after Exec() in PHP

In PHP, the exec() function executes a command and returns its output as a string. However, if the command produces errors, these are typically suppressed and not displayed. For handling such errors, understanding stderr streams is crucial.

Using proc_open to Read StdErr

To access stderr after executing a command, you can use the proc_open() function, which offers granular control over the execution process. It enables you to define input/output streams for stdin, stdout, and stderr.

Here's an example:

$descriptorspec = [
   0 => ["pipe", "r"],  // stdin
   1 => ["pipe", "w"],  // stdout
   2 => ["pipe", "w"],  // stderr
];

$process = proc_open('./test.sh', $descriptorspec, $pipes, dirname(__FILE__), null);

$stdout = stream_get_contents($pipes[1]);
fclose($pipes[1]);

$stderr = stream_get_contents($pipes[2]);
fclose($pipes[2]);

By reading from the $pipes[2] stream, you can access the stderr output produced by the executed command.

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