Printing to terminal while using output buffering in CLI PHP scipts

Question

I'm using command line PHP to build some files offline. To capture the script output I use the standard ob_start stuff:

ob_start();
// Echo lots of stuff
$content = ob_get_contents();
// Now the $content can be written to a file

However, I also want to print some messages to the terminal (for instance, warnings) while collecting the "main output" into the buffer. Is there a way to do this? It doesn't seem to be possible to pause the buffering for a while to print the terminal messages, and then continue the buffering from where it was left. Is there any workaround for this?

Answer 1

Use the php://stderr stream:

$f = fopen('php://stderr', 'w');
fputs($f, 'Output');

EDIT: Also, in CLI, there is a predefined STDERR constant:

fputs(STDERR, 'Output');

Answer 2

Just write to STDOUT or STDERR (both constants containing file pointer resources) using fputs():

ob_start();
echo 'Output buffer';
fputs(STDOUT, "Log message");
$x = ob_get_contents();
ob_end_clean();;

echo "X = $x";

Answer 3

It is possible to 'pause' an output buffer. Write the contents of the buffer to a variable, and end the buffer without flushing. Write some non-buffered output, and call ob_start() again. This method uses string concatenation, and it's a relatively dirty method. I prefer the other methods above my own for this reason.

But in either case, here's a small, working example:

<?php
ob_start();
 echo 'Buffered line 1.<br>';
$ob = ob_get_contents();
ob_end_clean();

echo 'Non-buffered line.<br>';

ob_start();
 echo 'Buffered line 2.<br>';
$ob .= ob_get_contents();
ob_end_clean();

echo 'Non-buffered line.<br>';

ob_start();
 echo 'Buffered line 3.<br>';
$ob .= ob_get_contents();
ob_end_clean();

echo 'Non-buffered line.<br>';

echo $ob;
?>