Re: [bug-gawk] When RS is null, POSIX states \n should be in FS, gawk only does that if FS is single char

[Ed Morton]

Sounds good, thanks for the quick response.

    Ed.

On 4/15/2019 8:52 AM, address@hidden wrote:
> Hi.
>
> Thanks for the report. This smells like a change in the POSIX
> standard, but I will have to research previous standards and also
> what the original AWK book says.
>
> Thanks,
>
> Arnold
>
> Ed Morton <address@hidden> wrote:
>
> > I just came across this where setting RS to null causes FS to include
> > `\n` if FS is a singe char but not otherwise:
> >
> >      $ printf '1:2\n3\n' | awk -F':' -v RS= '{for (i=1; i<=NF; i++) print
> >      i"/"NF, "<"$i">"}'
> >      1/3 <1>
> >      2/3 <2>
> >      3/3 <3>
> >
> >      $ printf '1::2\n3\n' | awk -F'::' -v RS= '{for (i=1; i<=NF; i++)
> >      print i"/"NF, "<"$i">"}'
> >      1/2 <1>
> >      2/2 <2
> >      3>
> >
> > with this gawk version:
> >
> >      $ awk --version
> >      GNU Awk 4.2.1, API: 2.0 (GNU MPFR 4.0.2, GNU MP 6.1.2)
> >      Copyright (C) 1989, 1991-2018 Free Software Foundation.
> >
> > and that makes sense given the gawk documentation
> > (https://www.gnu.org/software/gawk/manual/gawk.html#Multiple-Line) which
> > says (red/underline mine):
> >
> >      When RS is set to the empty string _/and /__FS is set to a single
> >      character_, the newline character always acts as a field separator.
> >      This is in addition to whatever field separations result from FS^
> >
> > but the POSIX spec (http://pubs.opengroup.org/onlinepubs/9699919799/) says:
> >
> >      *RS*
> >          The first character of the string value of *RS* shall be the
> >          input record separator; a <newline> by default. If *RS* contains
> >          more than one character, the results are unspecified. If *RS* is
> >          null, then records are separated by sequences consisting of a
> >          <newline> plus one or more blank lines, leading or trailing
> >          blank lines shall not result in empty records at the beginning
> >          or end of the input, and a <newline> shall always be a field
> >          separator, no matter what the value of *FS* is.
> >
> > gawk behaves the way I described with or without the `--posix` flag.
> > Shouldn't it add `\n` as a separator when RS is null regardless of the
> > value of FS like POSIX says? FWIW OSX/BSD awk on MacOS behaves the same
> > way that gawk does, idk about other awks.
> >
> >   ???????? Ed.