问题描述
我有一个简单的任务，已经花了几个小时试图弄清楚如何在bash脚本的curl调用中使用变量:
I have this simple task and I've spent a few hours already trying to figure out how can I use a variable inside a curl call within my bash script:
message="Hello there"
curl -X POST -H 'Content-type: application/json' --data '{"text": "${message}"}'
这是输出$ {message}，实际上是因为它在单引号内.如果我更改引号并在外部加双且在内部加单，则表示找不到命令:您好，然后找不到命令:那里.
This is outputting ${message}, literally because it's inside a single quote. If I change the quotes and put double outside and single inside, it says command not found: Hello and then command not found: there.
我该如何进行这项工作?
How can I make this work?
推荐答案
变量不会在单引号内扩展.用双引号重写:
Variables are not expanded within single-quotes. Rewrite using double-quotes:
curl -X POST -H 'Content-type: application/json' --data "{\"text\": \"${message}\"}"
请记住，必须将双引号中的双引号转义.
Just remember that double-quotes within double-quotes have to be escaped.
另一种变化可能是:
curl -X POST -H 'Content-type: application/json' --data '{"text": "'"${message}"'"}'
此行将单引号引起来，将${message}括在双引号中以防止单词分裂，然后以另一个单引号字符串结尾.那就是:
This one breaks out of the single quotes, encloses ${message} within double-quotes to prevent word splitting, and then finishes with another single-quoted string. That is:
... '{"text": "'"${message}"'"}'
^^^^^^^^^^^^
single-quoted string
... '{"text": "'"${message}"'"}'
^^^^^^^^^^^^
double-quoted string
... '{"text": "'"${message}"'"}'
^^^^
single-quoted string
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