[e12e]

Doesn't appear anyone has tried addressing before replacement - ie the simplest sed work-a-like - if you don't mind the leading ### is just:

  sed -n '/^### /p' 

I believe? (equivalent to grep).

Then eg:

  sed -nr '/^### /s/^.{4}(.*)/\1/p'

(or without the redundant addressing, just:)

  sed -nr 's/^### (.*)/\1/p'

[bewuethr]

You can simplify

    sed -nr 's/^.{4}(.*)/\1/'

to

    sed -nr 's/^.{4}//

And if you use a pattern for the address, you can repeat it in the substitution by using an empty pattern, so

    sed -nr '/^### /s/^.{4}(.*)/\1/p'

is the same as

    sed -nr '/^### /s/^.{4}//p'

is the same as

    sed -nr '/^### /s///p'

at which point I prefer just the substitution:

    sed -nr 's/^### //p'