使用具有不同引号级别和空格的变量构建命令字符串 [英] Building command strings using variables with various quote levels and spaces

问题描述

我有一个运行curl的脚本.如果字符串不为空，我希望能够选择添加-H参数.复杂的是报价和空格的水平.

I have a script that runs curl. I want to be able to optionally add a -H parameter, if a string isn't empty. What's complex is the levels of quoting and spaces.

caption="Test Caption"

if [ "${caption}" != "" ]; then 
    CAPT=-H "X-Caption: ${caption}"
fi

curl -A "$UA" -H "Content-MD5: $MD5" -H "X-SessionID: $SID" -H "X-Version: 1"  $CAPT http://upload.example.com/$FN

这个想法是CAPT变量为空，或包含所需的-H标头，格式与其他标头相同，例如-H "X-Caption: Test Caption"

The idea is that the CAPT variable is either empty, or contains the desired -H header in the same form as the others, e.g., -H "X-Caption: Test Caption"

问题是在运行时，它将分配解释为要执行的命令:

The problem is when run, it interprets the assignment as a command to be executed:

$bash -x -v test.sh
+ '[' 'Test caption' '!=' '' ']'
+ CAPT=-H
+ 'X-Caption: Test caption'
./test.sh: line 273: X-Caption: Test caption: command not found

我曾尝试在代码之前重置IFS，但这并没有改变.

I've tried resetting IFS before the code, but it didn't make a difference.

推荐答案

完成这项工作的关键是使用数组.

The key to making this work is to use an array.

caption="Test Caption"

if [[ $caption ]]; then 
    CAPT=(-H "X-Caption: $caption")
fi

curl -A "$UA" -H "Content-MD5: $MD5" -H "X-SessionID: $SID" -H "X-Version: 1"  "${CAPT[@]}" "http://upload.example.com/$FN"

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