How do you script/format a YAML file to add a new line above root level elements?-CodePudding

I have a YAML file for a Ruby on Rails configuration that is formatted like the below

default: &default
  api:
    my_id: test
    my_secret: test
development:
  <<: *default
  api:
    domain: some domain
  sso:
    url: some_url
qa:
  <<: *default
  api:

I would like to write a script that will add a new line above all the top level elements. So for instance when the script or command runs against the above, it would produce

default: &default
  api:
    my_id: test
    my_secret: test

development:
  <<: *default
  api:
    domain: some domain
  sso:
    url: some_url

qa:
  <<: *default
  api:

However when I run this command

perl -pi -e 's/^^[ ](.*)$/\n$1/g' yamlfile.yml

It adds a new line above every line, not just the root elements. What would be the proper way to add such a new line above only the top level elements?

CodePudding user response：

This should achieve what you wanted :

perl -pi -e 's/^\S/\n$&/' yamlfile.yml

CodePudding user response：

^^ is redundant, and [ ] is the opposite of what you want to match. I think you meant ^[^ ], which is better, but inserts a line at the top of the file.

Solution:

perl -i -pe's/^(?=\S)/\n/ if $. != 1' yamlfile.yml

A solution that reads in the whole file at once:

perl -i -0777pe's/\n\K(?=\S)/\n/g' yamlfile.yml

Neither of the above checks if there's an existing blank line. The following, on the other hand, normalizes blank lines precending top-level elements:

perl -i -0777pe's/^\n //; s/\n\K\n* (?=\S)/\n/g' yamlfile.yml