Erase the scrollback history.

gistfile1.php

/**
 * Erase the scrollback history.
 */
function clearScrollback () {
    if (php_sapi_name() !== 'cli') {
        throw new Exception('Use of function in invalid interface context.');
    }

    $term_program = getenv('TERM_PROGRAM');

    // https://en.wikipedia.org/wiki/Terminal_(OS_X)
    if (strpos($term_program, 'Apple_Terminal') === 0) {
        echo chr(27) . '[3J';
    // https://en.wikipedia.org/wiki/ITerm2
    } else if (strpos($term_program, 'iTerm') === 0) {
        echo chr(27) . ']50;ClearScrollback' . chr(7);
    } else {
        throw new Exception('Unknown Termimanl program.');
    }
}