Re: inconstancy with RS = "(\r?\n){2}"

[Ed Morton]

On 7/25/2021 4:47 AM, arnold@skeeve.com wrote:
> Greetings.
>
> Thank you for taking the time to make a bug report. In the future please
> send a concise description of the problem with a test program and data.
> It was hard for me to determine what you really think is the bug.
>
> It looks like your concern is with the need to enter EOF more than
> once from the terminal.
>
> Gawk is designed mainly for batch processing (from files or a pipe).
> Reading from a terminal with a complicated regexp as RS isn't the
> normal use case.  When RS is a regexp gawk may have to do lookahead in
> the input stream to be sure that the regexp has matched, and thus
> the need for multiple EOFs.
>
> In any case, I don't think there is an actual bug:
>
> $ od -c data
> 0000000   a  \n  \n  \n   b  \n  \n  \n  \n   c  \n  \n  \n  \n   d  \n
> 0000020
> $ ./gawk -v RS='(\r?\n){2}' -v ORS='|\n' '{ print }' < data
> a|
>
> b|
> |
> c|
> |
> d
> |
>
> This looks right to me.
>
> Thanks,
>
> Arnold

The problem occurs when reading from a terminal:

Good (no \r? in RS), every pair of `\n`s is recognized:
------------
$ gawk -v RS='(\n){2}' '{print "<"$0":"RT">"}'



<:

>


<:

>


<:

>
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Bad (with \r? in RS), no RS is every recognized:
--------------
$ gawk -v RS='(\r?\n){2}' '{print "<"$0":"RT">"}'






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Meanwhile if the input was coming from a pipe the RS including `\r?` 
would be recognized:
---------
$ printf '\n\n\n\n\n' | gawk -v RS='(\r?\n){2}' '{print "<"$0":"RT">"}'
<:

>
<:

>
<
:>
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Regards,

    Ed.