def _is_prefixed(cmd_line):
    """Whether the supplied command line has already been prefixed
    with an OS specific operation.
    """
    if cmd_line is None:
        raise ValueError('CommandLine is required field for task.')
    return cmd_line.startswith('cmd.exe /c') or cmd_line.startswith('cmd /c'
        ) or cmd_line.startswith('/bin/bash -c') or cmd_line.startswith(
        '/bin/sh -c')
