如何在不使用jq的Shell脚本中提取文本文件指定值

我有一个名为myfile.txt的文件，内容为JSON格式的项目状态数据：

{"projectStatus":{"status":"ERROR","conditions":[{"status":"ERROR","metricKey":"new_bugs","comparator":"GT","periodIndex":1,"errorThreshold":"0","actualValue":"2"},
{"status":"ERROR","metricKey":"new_reliability_rating","comparator":"GT","periodIndex":1,"errorThreshold":"1","actualValue":"3"},
{"status":"ERROR","metricKey":"new_security_rating","comparator":"GT","periodIndex":1,"errorThreshold":"1","actualValue":"2"},
{"status":"OK","metricKey":"new_maintainability_rating","comparator":"GT","periodIndex":1,"errorThreshold":"1","actualValue":"1"},
{"status":"ERROR","metricKey":"new_code_smells","comparator":"GT","periodIndex":1,"errorThreshold":"0","actualValue":"17"},
{"status":"ERROR","metricKey":"new_vulnerabilities","comparator":"GT","periodIndex":1,"errorThreshold":"0","actualValue":"2"},
{"status":"ERROR","metricKey":"coverage","comparator":"LT","errorThreshold":"90","actualValue":"80.3"},
{"status":"ERROR","metricKey":"new_coverage","comparator":"LT","periodIndex":1,"errorThreshold":"90","actualValue":"7.826086956521739"}],
"periods":[{"index":1,"mode":"previous_version","date":"2021-11-04T14:47:41+0000"}],"ignoredConditions":false}}

需要提取其中metricKey为"new_coverage"对应的actualValue值（即7.826086956521739），预期输出：

7.826086956521739

我尝试过以下sed命令但未成功：

sed -n 's/"metricKey":"new_coverage" "actualValue": //p' myfile.txt 

注意：不允许使用jq或Python、JavaScript等通用脚本语言。

方法1：修正后的sed命令 #

原命令失效的原因是："metricKey":"new_coverage"与"actualValue"之间不是空格，而是包含逗号和空格；同时没有匹配actualValue值的引号结构。使用以下命令可实现需求：

sed -n 's/.*"metricKey":"new_coverage".*"actualValue":"\([^"]*\)".*/\1/p' myfile.txt

核心逻辑：

• .*：匹配任意长度的前置内容，快速定位到目标metricKey
• "actualValue":"\([^"]*\)"：用分组捕获actualValue引号内的所有内容（[^"]*表示匹配除引号外的任意字符）
• \1：仅输出捕获到的目标值

方法2：使用awk命令 #

如果觉得sed正则过于复杂，也可以用awk处理：

awk -F'"' '/"metricKey":"new_coverage"/{for(i=1;i<=NF;i++){if($i=="actualValue"){print $(i+2)}}}' myfile.txt

核心逻辑：

• -F'"'：以双引号作为字段分隔符
• 匹配包含目标metricKey的行后，遍历所有字段，找到值为actualValue的字段，输出其后第2个字段（即目标值）

内容的提问来源于stack exchange，提问作者Zero5