[SOLVED] Regex in sed command does not work properly

Issue

I have a yaml file like below.

test:
  test_1:
        fact_1: Present
        fact_2: value_1
        tag: tagvalue
  test_2:
        fact_1: NotPresent
        fact_2: null
        tag: null
  test_3:
        fact_1: Present
        fact_2: value_2
        tag: 1.1
        fact_3: 60
  test_4:
        fact_1: Present
        fact_2: value_3
        tag: 5.1

I want to update the tag under test_1 section in this yaml file. Note that I don't know the current value of that tag and also I don't know the exact keys and the order of the keys in this yaml file. Also this is a sub section of my full yaml file.

I have tried to use a regular expression to identify this tag value and then update the file with sed command.

sed -i 's/\(\stest_1:[\s\S]*?tag\s*:\s*)(\S+)/\1new_tag/' test.yaml

When I test the regex separately it identified the test_1 section. But when I execute above sed command it doesn't change anything. Can I know what is the issue here?

Solution

sed is not a YAML parser, but instead a text line stream oriented tool.

With Python or go yq:

$ yq '.test.test_1.tag="new_tag"' file.yaml 
{
  "test": {
    "test_1": {
      "fact_1": "Present",
      "fact_2": "value_1",
      "tag": "new_tag"
    },
    "test_2": {
      "fact_1": "NotPresent",
      "fact_2": null,
      "tag": null
    },
    "test_3": {
      "fact_1": "Present",
      "fact_2": "value_2",
      "tag": 1.1,
      "fact_3": 60
    },
    "test_4": {
      "fact_1": "Present",
      "fact_2": "value_3",
      "tag": 5.1
    }
  }
}

Answered By - Gilles Quénot

Answer Checked By - Dawn Plyler (WPSolving Volunteer)