Bash- if子句无法正常工作 [英] Bash- if clause doesn't work correctly

问题描述

我想制作一个关闭脚本，它无法按预期工作.这就是我写的.

I want to make a shutdown script and it doesn't work as intended. This is what I wrote.

echo "Wanna shutdown (y/n)?"

 read ANSWER

if [ $ANSWER=="y" ]
     then
        sudo shutdown -P now
else 
    printf "Something...."

无论我按什么按钮，它都会关闭.为什么?

whatever i press it just shuts down. Why?

推荐答案

您需要在==运算符周围放置空格.否则，测试表达式只能是一个单词，并且所有非空单词都可以成功测试.

You need to put spaces around the == operator. Otherwise the test expression is a single word, and all non-empty words test successfully.

此外，如果希望便携，则应使用=而不是==.并且总是用双引号括起变量扩展是明智的，因为[不会为您这样做.

In addition, if you wish to be portable, you should use = instead of ==. And it is always wise to double quote variable expansions because [ won't do that for you.

if [ "$ANSWER" = y ]; then

另一方面，如果您使用的是bash(或ksh或zsh)，则可以使用更宽容的[[条件表达式:

On the other hand, if you are using bash (or ksh or zsh) you could use the more forgiving [[ conditional expression:

if [[ $ANSWER = y ]]; then

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