protected function getPHPExecutable()
    {
        $validExecutable = false;
        $output = array();
        $exec = 'php';
        if ( !empty( $this->Options['php-exec'] ) )
        {
            $exec = $this->Options['php-exec'];
        }
        exec( $exec . ' -v', $output );

        if ( count( $output ) && strpos( $output[0], 'PHP' ) !== false )
        {
            $validExecutable = true;
            $this->Executable = $exec;
        }

        while( !$validExecutable )
        {
            $input = readline( 'Enter path to PHP-CLI executable ( or [q] to quit )' );
            if ( $input === 'q' )
            {
                $this->Script->shutdown( 0 );
            }

            exec( $input . ' -v', $output );

            if ( count( $output ) && strpos( $output[0], 'PHP' ) !== false )
            {
                $validExecutable = true;
                $this->Executable = $input;
            }
        }
    }