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

[Zachary Santer]

In case people start to find this email chain, looking for a way to do what
I did:

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

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

The last thing worked, but kind of accidentally. I was treating the pair of
'/\r$/{ } /\r$/!{ }' like if-else, but the second one would be considering
the pattern buffer potentially modified within the prior block. What I have
here with branch commands and labels is actually doing if-else.

On Mon, Jul 25, 2022 at 8:58 AM Zachary Santer <zsanter@gmail.com> wrote:

> 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
>