Question

What would be the differnce in php command line app of just echoing or printf etc some string as opposed to getting sdtout stream and writing to it i.e.

$stdout = fopen('php://stdout', 'w');

Answer 1

The first thing that comes to mind for me is output buffering. echo and print interface with the output buffering mechanism, but directly writing to stdout bypasses it.

Consider this script:

<?php
$stdout = fopen('php://stdout', 'w');
ob_start();
        echo "echo output\n";
        fwrite($stdout, "FWRITTEN\n");
        echo "Also echo\n";
$out = ob_get_clean();
echo $out;

which outputs:

FWRITTEN
echo output
Also echo

which demonstrates that echo is buffered, and fwrite is not.