bash - echo $(printf ...) dropping whitespace/formatting

Question

I was using printf to format a number in bash:

$ printf -- ">>%4d
" 1
>>   1

This works fine, but when i do the same thing in a subshell:

$ echo $(printf -- ">>%4d
" 1)
>> 1

Why are the spaces removed? I have absolutely no idea.

Answer 1

The sub-shell isn't doing it. Not directly.

The issue here is that you aren't quoting the sub-shell result. As such the shell is word-splitting the resulting text (which drops extraneous spaces) and then hands a list of words to echo which happily spits them back out at you (without the extra spaces).

This is essentially no different than running echo 1 and wondering where the extra spaces went.

My answer here discusses this a bit as well.