Re: Add missing final line ending to files - LF or CRLF

[Zachary Santer]

On Mon, Jul 25, 2022 at 3:58 AM Zachary Santer <zsanter@gmail.com> wrote:
>
> Along with removing trailing tabs and spaces from all lines.
>
> sed_expr='
> s/[[:blank:]]+(\r?)$/\1/
> ${
>   /\r$/!{
>     x
>     s/^[^\r]*(\r?)$/\1/
>     x
>     G
>     s/\n//
> #   a\
> #
>   }
> }
> h
> '
>
> sed --binary --regexp-extended --in-place --expression="${sed_expr}" -- "${1}"

If the final newline I'm getting in this case is coming from the
contents of hold space which I'm appending on, I wasn't able to get
rid of it by changing 's/\n//' into 's/\n//g', but I guess that kind
of makes sense.

I finally settled on this, which is a lot easier to reason about:

sed_expr='
s/[[:blank:]]+(\r?)$/\1/
${
  /\r$/!{
    x
    /\r$/{
      x
      s/$/\r/
    }
    /\r$/!{
      x
    }
  }
}
h
$a\'

sed --binary --regexp-extended --in-place --expression="${sed_expr}" -- "${1}"

To use '$a/' like this, it has to be the very last argument in the
expression. Luckily for me, the h command could come before it. The
idea came from 
here<https://unix.stackexchange.com/questions/31947/how-to-add-a-newline-to-the-end-of-a-file>.

Zack