'Execute a shell command'

def do_shell(self, arg):

    try:
        retcode = subprocess.call(arg, shell=True)
        del retcode
    except OSError as e:
        self.io.print_error(('Execution    failed:    ' + e.message))
    except KeyboardInterrupt:
        self.io.print_warning('Execution    aborted    by    user:    Ctrl-c')
