将布尔表达式的结果存储到变量中 [英] Storing into variable a result of boolean expression

问题描述

是否可以将布尔表达式的结果连续存储到变量中?

Is it possible to continuously store a result of boolean expression into a variable?

示例

ret=0
for each in aCollection do
    executeSomeCommand;
    # vvv compare stored value against a returned value and store it again
    ret=$ret || $?;
done;
[[ ret = 0 ]] && echo "success"

问题在于，如果 $?为 1 ，则 $ ret 仍包含零

The problem is that if $? is 1, then $ret still contains zero

ret=0
echo $ret # --> 0
ret=$ret || 1
echo $ret # --> 0 (should be 1)

推荐答案

您遇到分组/操作顺序问题.当你做

You have a grouping/order of operations problem. When you do

ret=$ret || 1

首先执行 ret = $ ret ，然后获取结果，然后对 1 进行 || ，然后忽略结果其中.因此，您要做的分配工作的唯一部分就是再次将 ret 分配给它自己.

it is first doing ret=$ret and then taking the result of that and doing an || with 1 then ignoring the result of that. So the only part of the assignment you're doing is assigning ret to itself again.

您想要做的是 $ ret ||1 部分并存储结果，因此您需要使用像

What you want is to do the $ret || 1 part and store the result, so you need parens like

ret=$(($ret || 1))

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