How can I create folders in folders in terminal

You may want to put on your {curly} braces for this one

For the sake of this argument we will pretend ./music doesn't exist

In your base directory for ./music we will use the -p command to create sub-directories where needed and the curly braces will be used to create a small array

The command -p is short for parent, if it's easier to remember you may use --parent instead

mkdir -p ./music/{"1. Albums","2. EP","3. Singles","4. Live"}

If you wish to play around with this you may, for example

mkdir -p ./folder/prefix{a{1/only,2,3},b,c}suffix/more{z,y,x}

You have nested expressions, you may insert the braces in to the middle of a string and you can also allow the subdirectory to follow suit, and you can be specific with your sub directories for a particular array

I suggest you make a file somewhere where you can make your own templates with such commands and give them descriptions

Visit this page for more information https://www.linuxjournal.com/content/bash-brace-expansion and https://www.linux.com/tutorials/all-about-curly-braces-bash/

Sure, execute this in the music folder where the artist folders are:

for artist in */; do
   for folder in "1. Albums" "2. EP" "3. Singles" "4. Live"; do
      mkdir "$artist/$folder"
   done
done

You can execute this on your CLI, or you can make it a shell script by adding #!/bin/sh as the first line and saving it in a file. Don't forget to make the file executable.

As for what it does: it iterates over all directories (*/) within the current directory, then for each of these directories, iterates over the desired subfolder (the second for), and then makes the desired (relative) subfolder.