From: Felipe Contreras <felipe.contreras@gmail.com>
To: "Lawrence Velázquez" <larryv@zsh.org>
Cc: Zsh Users <zsh-users@zsh.org>
Subject: Discrepancy in IFS handling (zsh is *not* POSIX compliant)
Date: Thu, 30 Mar 2023 06:10:48 -0600 [thread overview]
Message-ID: <CAMP44s2KB_DbemKs9jFu=0yy06DaC+H1W2SiueEoQ-rtHOp-NA@mail.gmail.com> (raw)
In-Reply-To: <D5349F8B-5D85-4E62-9FBC-520181FEC6A9@zsh.org>
On Thu, Mar 30, 2023 at 6:05 AM Lawrence Velázquez <larryv@zsh.org> wrote:
>
> On Mar 30, 2023, at 7:13 AM, Felipe Contreras <felipe.contreras@gmail.com> wrote:
>
> However, this is what POSIX says:
>
> 3.b. Each occurrence in the input of an IFS character that is not
> IFS white space, along with any adjacent IFS white space, shall
> delimit a field, as described previously.
>
> We ignore all the white space stuff (since we are not using white
> spaces), and thus:
>
> Each occurrence in the input of an IFS character shall delimit a field.
>
> In zsh each occurrence of a comma does delimit a field (4 commas, 5
> fields), which to me is what POSIX says should happen.
>
> So in this particular case it seems zsh is complying with POSIX (even
> in zsh mode), and all other shells are not.
>
>
> Before the excerpt you quoted, XCU 2.6.5 says: “The shell shall treat each character of the IFS as a delimiter and use the delimiters as field terminators to split the results of parameter expansion, command substitution, and arithmetic expansion into fields.”
>
> The bash/dash/ksh behavior is not unreasonable if the phrase “field terminators” is interpreted strictly.
>
> In any case, I believe the standard intends to describe the ksh behavior:
Yes, I was about to click send to point that out.
So if IFS contains terminators, and not separators, this should
generate 5 fields:
IFS=';'
str='foo;bar;;roo;;'
printf '"%s"\n' $str
For: 'foo;' 'bar;' ';' 'roo;' ';'
In which case bash is correct, zsh generates 6 fields, so it's not.
Seems weird that a variable called Internal Field Separator is not a
*separator*, but a terminator.
I'm changing the subject to reflect that.
Cheers.
--
Felipe Contreras
next prev parent reply other threads:[~2023-03-30 12:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 11:11 Discrepancy in IFS handling (zsh is " Felipe Contreras
2023-03-30 12:05 ` Lawrence Velázquez
2023-03-30 12:10 ` Felipe Contreras [this message]
2023-03-30 14:49 ` Discrepancy in IFS handling (zsh is *not* " Ray Andrews
2023-03-30 15:09 ` Felipe Contreras
2023-03-30 15:31 ` Ray Andrews
2023-03-30 14:57 ` Bart Schaefer
2023-03-30 15:34 ` Felipe Contreras
2023-03-31 20:16 ` Discrepancy in IFS handling (zsh is " Felipe Contreras
2023-04-01 19:20 ` Lawrence Velázquez
2023-03-31 16:38 ` Thomas Paulsen
2023-03-31 20:18 ` Felipe Contreras
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