if (class_exists('Tidy')) {

      //.... do the needful. truncated for clarity

} else {
    // using Tidy on the command line expects input from STDIN
    // We'll use printf which is more consistent than echo which varies
    // We want something like the following
    //$result =  shell_exec('printf "$content" | tidy');
    $html = $this->mContent;
    // don't need this escaping since we're not using shell_exec
    // $html = str_replace(array('\\', '%'), array('\\\\', '%%'), $html);
    
    $tidy = "/usr/bin/tidy";
    // only by passing the options as a long string worked.
    // also, $this->mTidyErrors will never populate unless we explicitly 
    // trap STDERR
    // 2>&1 1> /dev/null
    $cmd = "$tidy -quiet -indent -ashtml $shellConfig";
    $tidy = '/usr/bin/tidy -quiet -indent -ashtml  --drop-empty-paras 1 --drop-font-tags 1 --enclose-block-text 1 --enclose-text 1 --fix-backslash 1 --fix-bad-comments 1 --fix-uri 1 --hide-comments 1 --merge-divs 1 --merge-spans 1 --repeated-attributes keep-first --show-body-only 1 --show-errors 0 --show-warnings 0 --indent 0 --wrap 120 --tidy-mark 0 --write-back 0';
    // $escaped_command = escapeshellcmd($cmd);
    // echo "executing $escaped_command";
    // $this->mContentTidy = $this->mContent = shell_exec("printf '$html' | $escaped_command");
    $descriptorspec = array(
        0 => array("pipe", "r"), // stdin is a pipe that the child will read from
        1 => array("pipe", "w"), // stdout is a pipe that the child will write to
        2 => array("pipe", "w")  // stderr is a pipe that the child will write to
        // 2 => array("file", "/tmp/error-output.txt", "a") // stderr is a file to write to
    );