How can I avoid removing line breaks when updating a YAML file?

[ldosdevel01-max]

title: this is a long
  long title
a: one

Running:

yq -i e '(.a) = "two"' ~/1.yaml

Results in:

title: this is a long long title
a: two

Expected (preserving line break):

title: this is a long
  long title
a: two

[roonakyadav]

yq is re-serializing the YAML, so the physical line break in a plain scalar is not preserved. In YAML, a line break inside a plain scalar is folded into a space, so:

title: this is a long
long title

has the same value as:

title: this is a long long title

If you need the newline to be semantically preserved, use a literal block scalar instead:

title: |
this is a long
long title

yq supports controlling a node's YAML style with the style operator, e.g.:

yq -i '.title style="literal" | .a = "two"' 1.yaml

So if the requirement is to preserve the exact original formatting of an existing plain scalar while modifying another field, yq does not currently provide a general formatting-preservation mechanism for that case; using a round-tripping YAML tool would be more appropriate.