Bash 脚本 - If 语句未按预期运行

Question

这是我第一次玩 bash 脚本，但我就是不明白为什么这个 if 语句不起作用。无论我将什么输入输入 choice 变量作为输入，我总是得到 returned 第一个 echo，它应该只在我输入 yes 或 no 以外的任何内容时执行。

我试过删除括号，用双引号引起来，但我就是无法理解这一点。

代码如下：

#!/bin/bash

read -p 'Would you like to take driving lessons: ' choice
read -p 'Type your age: ' age

if [ $choice != 'yes' ] || [ $choice != 'no' ] 
then 
  echo 'Your choice must be either yes or no'
fi

这是输出：

$ ./test.sh        
Would you like to take driving lessons: yes
Type your age: 46
Your choice must be either yes or no
                                                                                                                                                                                                                                                                                                                           
$ ./test.sh        
Would you like to take driving lessons: no
Type your age: 63
Your choice must be either yes or no
                                                                                                                                                                                                                                                                                                                           
$ ./test.sh
Would you like to take driving lessons: dgdgf
Type your age: 76
Your choice must be either yes or no

只有最后一个运行应该 return 回显语句。

Answer 1

你们非常亲密。当它不等于时，您需要 &&。这有效：

#!/bin/bash

read -p 'Would you like to take driving lessons: ' choice
read -p 'Type your age: ' age

if [ $choice != 'yes' ] && [ $choice != 'no' ];
then
  echo 'Your choice must be either yes or no'
fi

它给出以下输出：

~ bash test.sh
Would you like to take driving lessons: yes
Type your age: 432
~ bash test.sh
Would you like to take driving lessons: fdsa
Type your age: 32
Your choice must be either yes or no

Answer 2

你应该这样写：

#!/bin/bash

read -p 'Would you like to take driving lessons: ' choice
read -p 'Type your age: ' age

if [ $choice != 'yes' ] && [ $choice != 'no' ]
then
  echo 'Your choice must be either yes or no'
fi

Bash 脚本 - If 语句未按预期运行

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