how to redirect STDOUT to a file in PHP?

Question

The code below almost works, but it's not what I really meant:

ob_start();
echo 'xxx';
$contents = ob_get_contents();
ob_end_clean();
file_put_contents($file,$contents);

Is there a more natural way?

Answer 1

It is possible to write STDOUT directly to a file in PHP, which is much easier and more straightforward than using output bufferering.

Do this in the very beginning of your script:

fclose(STDIN);
fclose(STDOUT);
fclose(STDERR);
$STDIN = fopen('/dev/null', 'r');
$STDOUT = fopen('application.log', 'wb');
$STDERR = fopen('error.log', 'wb');

Why at the very beginning you may ask? No file descriptors should be opened yet, because when you close the standard input, output and error file descriptors, the first three new descriptors will become the NEW standard input, output and error file descriptors.

In my example here I redirected standard input to /dev/null and the output and error file descriptors to log files. This is common practice when making a daemon script in PHP.

To write to the application.log file, this would suffice:

echo "Hello world
";

To write to the error.log, one would have to do:

fwrite($STDERR, "Something went wrong
"); 

Please note that when you change the input, output and error descriptors, the build-in PHP constants STDIN, STDOUT and STDERR will be rendered unusable. PHP will not update these constants to the new descriptors and it is not allowed to redefine these constants (they are called constants for a reason after all).