在变量分配的RHS中引用与不引用变量 [英] Quoting vs not quoting the variable on the RHS of a variable assignment

问题描述

在shell脚本中，将一个变量分配给另一个变量时，这两者之间有什么区别?

In shell scripting, what is the difference between these two when assigning one variable to another:

a=$b

和

a="$b"

什么时候应该在另一个上使用?

and when should I use one over the other?

推荐答案

我认为这里没有太大区别.是的，建议在引用变量时将其括在双引号中.但是，在您的问题中似乎未引用$x.

I think there is no big difference here. Yes, it is advisable to enclose a variable in double quotes when that variable is being referenced. However, $x does not seem to be referenced here in your question.

y=$x本身并不影响空白的处理方式.只有在实际使用$y时，引用才有意义.例如:

y=$x does not by itself affect how whitespaces will be handled. It is only when $y is actually used that quoting matters. For example:

$ x=" a    b "
$ y=$x
$ echo $y
a b
$ echo "$y"
 a    b

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