code: public function exec($command)
      {
          switch( $this->driver )
          {
              case 'exec':
                  $return = exec($command, $this->output, $this->return);
              break;
  
              case 'shell_exec':
              case 'shell'     :
                  $return       = shell_exec($command);
                  $this->output = $this->_split($return);
                  $this->return = 0;
              break;
  
              case 'system':
                  $return       = Buffering\Callback::do(function() use($command) {system($command, $this->return);});
                  $this->output = $this->_split($return);
              break;
  
              case 'ssh':
                  $ssh = Singleton::class('ZN\Remote\SSH');
                  $ssh->run($command);
                  $this->output = $this->_split($return = $ssh->output());
                  $this->return = 0;
              break;
          }
  
          return $return ?? false;
      }
docs: Execute
  
  @param string $command
  
  @return string|false