将JSON直接存储在带有变量的bash脚本中吗? [英] Store JSON directly in bash script with variables?

问题描述

在我的开头，我说不，找到一种不同的方式来做这件事"在这里是可以接受的答案.

I'm going to preface by saying that "no, find a different way to do it" is an acceptable answer here.

是否存在一种可靠的方法来将少量JSON存储在bash变量中，以便在从同一脚本运行的AWS CLI命令中使用?

Is there a reliable way to store a short bit of JSON in a bash variable for use in a AWS CLI command running from the same script?

我将在Jenkins上运行一项作业，该作业正在更新AWS Route53记录，这需要使用记录中的更改进行UPSERTing JSON文件.因为它是从Jenkins运行的，所以没有本地存储可以保存此文件，因此我非常想避免每次运行该项目时(每个小时一次)都需要进行git checkout.

I'll be running a job from Jenkins that's updating an AWS Route53 record, which requires UPSERTing a JSON file with the change in records. Because it's running from Jenkins, there's no local storage where I can keep this file, and I'd really like to avoid needing to do a git checkout every time this project will run (which will be once an hour).

理想情况下，考虑到Jenkins的设置，将数据存储在变量($foo)中并作为change-resource-record-sets命令的一部分进行调用将是最方便的，但是我不完全了解如何在内部引用/存储JSON. bash-能安全完成吗?

Ideally, storing the data in a variable ($foo) and calling it as part of the change-resource-record-sets command would be most convenient given the Jenkins setup, but I'm unfamiliar with exactly how to quote/store JSON inside bash - can it be done safely?

在这种情况下，以下是特定的JSON；

The specific JSON in this case is the following;

{"Comment":"Update DNSName.","Changes":[{"Action":"UPSERT","ResourceRecordSet":{"Name":"alex.","Type":"A","AliasTarget":{"HostedZoneId":"######","DNSName":"$bar","EvaluateTargetHealth":false}}}]}

作为一个复杂的问题，需要扩展DNSName值-$bar.

As an added complication the DNSName value - $bar - needs to be expanded.

推荐答案

您可以使用此处文档:

foo=$(cat <<EOF
{"Comment":"Update DNSName.","Changes":[{"Action":"UPSERT","ResourceRecordSet":{"Name":"alex.","Type":"A","AliasTarget":{"HostedZoneId":"######","DNSName":"$bar","EvaluateTargetHealth":false}}}]}
EOF
)

通过在第一行中保留EOF的位置，here-doc的内容将进行参数扩展，因此您的$bar会扩展为您在其中放置的内容.

By leaving EOF in the first line unquoted, the contents of the here-doc will be subject to parameter expansion, so your $bar expands to whatever you put in there.

如果JSON中可以有换行符，则可以使其更具可读性:

If you can have linebreaks in your JSON, you can make it a little more readable:

foo=$(cat <<EOF
{
  "Comment": "Update DNSName.",
  "Changes": [
    {
      "Action": "UPSERT",
      "ResourceRecordSet": {
        "Name": "alex.",
        "Type": "A",
        "AliasTarget": {
          "HostedZoneId": "######",
          "DNSName": "$bar",
          "EvaluateTargetHealth": false
        }
      }
    }
  ]
}
EOF
)

甚至(每行的第一个缩进必须是制表符)

or even (first indent on each line must be a tab)

foo=$(cat <<-EOF
    {
      "Comment": "Update DNSName.",
      "Changes": [
        {
          "Action": "UPSERT",
          "ResourceRecordSet": {
            "Name": "alex.",
            "Type": "A",
            "AliasTarget": {
              "HostedZoneId": "######",
              "DNSName": "$bar",
              "EvaluateTargetHealth": false
            }
          }
        }
      ]
    }
    EOF
)

并显示其存储方式，包括引号(假设bar=baz):

and to show how that is stored, including quoting (assuming that bar=baz):

$ declare -p foo
declare -- foo="{
  \"Comment\": \"Update DNSName.\",
  \"Changes\": [
    {
      \"Action\": \"UPSERT\",
      \"ResourceRecordSet\": {
        \"Name\": \"alex.\",
        \"Type\": \"A\",
        \"AliasTarget\": {
          \"HostedZoneId\": \"######\",
          \"DNSName\": \"baz\",
          \"EvaluateTargetHealth\": false
        }
      }
    }
  ]
}"

因为这会扩展一些外壳元字符，如果您的JSON包含类似`的内容，您可能会遇到麻烦，因此，也可以直接分配，但是要小心在$bar周围加上引号:

Because this expands some shell metacharacters, you could run into trouble if your JSON contains something like `, so alternatively, you could assign directly, but be careful about quoting around $bar:

foo='{"Comment":"Update DNSName.","Changes":[{"Action":"UPSERT","ResourceRecordSet":{"Name":"alex.","Type":"A","AliasTarget":{"HostedZoneId":"######","DNSName":"'"$bar"'","EvaluateTargetHealth":false}}}]}'

请注意$bar的引号:是

"'"$bar"'"
│││    │││
│││    ││└ literal double quote
│││    │└ opening syntactical single quote
│││    └ closing syntactical double quote
││└ opening syntactical double quote
│└ closing syntactical single quote
└ literal double quote

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