Hello,
  we use CYGWIN in our application, and there are a lot of shell-script
that use this sintax. In Windows environment, is normat that the End-Line
terminator is CRLF e not LF.

Regarding your question:

1) Can you test your sed program with version 4.2.2 ?
    R: Yes, same problems

2) Does the problem still happen if you use the following?   sed '/^$/d'
    R:: same problems

3.1. Which windows version are you using?
       Tested on Windows server 2012, Windows Server 2016, Windows 7 (all
64 bit)

3.2. Which cygwin version are you using?
       uname -a ->  CYGWIN_NT-10.0-WOW ITP-WDK2020 2.9.0(0.318/5/3)
2017-09-12 10:41 i686 Cygwin

3. Can you try the same sed command, but add the '--binary' flag,   if does
it show the same results?
     R:: same problems


Regards

Mauro

Il giorno gio 25 gen 2018 alle ore 22:59 Assaf Gordon <assafgordon@gmail.com>
ha scritto:

> Hello,
>
> On Thu, Jan 25, 2018 at 01:25:35PM +0000, Mauro Rigoni wrote:
> > with the last x86_32 version of sed (windows platform) the
> > following pattern
> >
> > sed '\?^$?D'
> >
> > don’t remove blank line from file if the file is in DOS format. In the
> > previous version 2.2 this command working.
>
> First,
> Sed version 2.X is more than 20 years old. It is not the previous version.
> The previous (and most common) version is version 4.2.2 from 2012.
> Can you test your sed program with version 4.2.2 ?
>
>
> Second,
> A question about your sed program:
> Does the problem still happen if you use the following?
>    sed '/^$/d'
>
> That is, regex with slashes (instead of '\?')
> and using lower-case 'd' (simple delete command)
> instead of 'D' (which is slightly more complicated
> and deals with multilined buffers).
>
>
> Third,
> I do not have access to a windows machine, so a bit more information
> is needed:
> 1. Which windows version are you using?
> 2. Which cygwin version are you using?
> (I assume it is cygwin based on the version string)
> 3. Can you try the same sed command, but add the '--binary' flag,
>    if does it show the same results?
>
> For reference,
> there is are two bug reports related to newlines with sed on windows.
> https://bugs.gnu.org/25459 and https://bugs.gnu.org/26879 .
>
> Specifically, note here
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=26879#12
> where Eric Blake mentions that cygwin modified some internal
> behaviour related to binary-vs-text files in February 2017.
>
>
> regards,
>  - assaf
>
-- 

Saluti
Mauro Rigoni