Reports

Thank you very much for providing examples and explanations! Finally I will use it like this:

perl -0777 -pe 's/(- section:[\s\S]*?)"MARKER"/$1"MARKER"\n$1"NEW MARKER 2"\n$1"NEW MARKER 3"/g' input.txt

My goal was to find the first block and duplicate it with different value: "MARKER".

Perfect!

Final result:

Some content ...
- section:
this is some text
this is some more text
value: "MARKER"
- section:
this is some text
this is some more text
value: "NEW MARKER 2"
- section:
this is some text
this is some more text
value: "NEW MARKER 3"
- another section:
this is some text
this is some more text
value: "M7"
- section:
this is some text
this is some more text
value: "MARKER"
- section:
this is some text
this is some more text
value: "NEW MARKER 2"
- section:
this is some text
this is some more text
value: "NEW MARKER 3"
... content goes on

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