Generate full paths from nested (for example yaml) directory structure

Question

I try to write script in shell/bash that will convert yaml directory structure to full paths (for further mkdir -p it). Yaml is my choice because of human-editability. Structure example is:

- Downloads
    - Music
    - Movies
- University
    - First year
        - English
        - Maths
    - Second year

So I want to replace first-level with current dir (realpath .), for example, /home/maeda/Downloads, second with parent dir's full path (for example, /home/maeda/Downloads/Music)

So I want to achieve this result:

/home/maeda/Downloads
/home/maeda/Downloads/Music
/home/maeda/Downloads/Movies
/home/maeda/University
/home/maeda/University/First year
/home/maeda/University/First year/English
/home/maeda/University/First year/Maths
/home/maeda/University/Second year

How to achieve it?

Answer 1

Assuming that your YAML file is valid, such as

Downloads:
    Music:
    Movies:
University:
    First year:
        English:
        Maths:
    Second year:

you may use

yq -r --arg prefix "$(realpath .)" 'paths | [ $prefix, .[] ] | join("/")' file.yaml

where yq is from https://kislyuk.github.io/yq/

This uses a jq expression to get the "paths" from the document. A "path" in this context is a representation of any specific entry in the document itself, so the path of the First year array is the array [ 'University', 'First year' ] (written using JSON notation).

These path arrays may be joined with / as the delimiter using join("/").

I'm also passing the output of realpath . into yq as the value of the internal variable $prefix. This value is added to the front of each of the path arrays before passing them through join("/"), which means that it will be prepended to the pathnames outputted by the yq command.