bash 中带引号和不带引号的相同值相等

Question

我有这个代码

#!/bin/bash
today=$(date +'%Y-%m-%d')
date_in_config=$(cat config.json  | jq ".date")
echo $date_in_config
echo $today

if [ $date_in_config == $today ];then
  echo "Same date"
else
  echo "different"
fi

config.json

{
  "date": "2021-03-24",
  "session": "0"
}

我一直在比较日期。我从上面的代码得到的输出是

"2021-03-24"
2021-03-24
different

我做错了什么？

Answer 1

显然您已经发现问题所在：对于 Bash（以及我能想到的任何其他编程语言），"x" 与 x 不同。

把双引号放在today:
```
today=$(date +'"%Y-%m-%d"')
```

或检索JSON信息时去掉引号：

date_in_config=$(jq -r ".date" < config.json)

并记得引用您的变量扩展，如 Shellcheck would have told you. Also get rid of the == bashism（可选，为了便于携带）。

[ "$date_in_config" = "$today" ]

bash 中带引号和不带引号的相同值相等

Equality for same value with and without quotes in bash

bash

comparison

json

date

quoting