How to prevent yq removing comments and empty lines?

Question

Here Edit yaml objects in array with yq. Speed up Terminalizer's terminal cast (record) I asked about how to edit yaml with yq. I received the best answer. But by default yq removes comments and empty lines. How to prevent this behavior?

input.yml

# Specify a command to be executed
# like `/bin/bash -l`, `ls`, or any other commands
# the default is bash for Linux
# or powershell.exe for Windows
command: fish -l

# Specify the current working directory path
# the default is the current working directory path
cwd: null

# Export additional ENV variables
env:
  recording: true

# Explicitly set the number of columns
# or use `auto` to take the current
# number of columns of your shell
cols: 110

execute

yq -y . input.yml

result

command: fish -l
cwd: null
env:
  recording: true
cols: 110

Answer 1

In some limited cases you could use diff/patch along with yq.
For example if input.yml contains your input text, the commands

$ yq -y . input.yml > input.yml.1
$ yq -y .env.recording=false input.yml > input.yml.2
$ diff input.yml.1 input.yml.2 > input.yml.diff
$ patch -o input.yml.new input.yml < input.yml.diff

creates a file input.yml.new with comments preserved but recording changed to false:

# Specify a command to be executed
# like `/bin/bash -l`, `ls`, or any other commands
# the default is bash for Linux
# or powershell.exe for Windows
command: fish -l

# Specify the current working directory path
# the default is the current working directory path
cwd: null

# Export additional ENV variables
env:
  recording: false

# Explicitly set the number of columns
# or use `auto` to take the current
# number of columns of your shell
cols: 110