该错误通常发生在为命令输入了不正确的开关或单字符开关组合时。

This error generally occurs when a incorrect switch or combination of single character switches has been entered for a command.

youdao

如果没有 -CA 开关，Perl 就会认为输入数据是字符 199。

Without -CA, Perl thinks the input was character 199.

youdao

幸运的是，Expect提供了各种有价值的调试开关，以报告其交互过程；这正是我确定CCNA01所生成的各种字符的方法。

Luckily, Expect has helpful debugging switches to report on its interactions; that's how I determined exactly what characters CCNA01 was emitting.

youdao