[debbugs-tracker] bug#9507: closed (cut bug?)

[GNU bug Tracking System]

Your message dated Wed, 14 Sep 2011 10:52:45 -0600
with message-id <address@hidden>
and subject line Re: bug#9507: cut bug?
has caused the debbugs.gnu.org bug report #9507,
regarding cut bug?
to be marked as done.

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-- 
9507: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=9507
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> --- Begin Message ---
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> Subject: 
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> cut bug?
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> Date: 
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> Wed, 14 Sep 2011 17:20:20 +0100
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> Hi,
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> I'm sure this must have been spotted before, but
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>     cut -f2,1
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> produces the fields in the order 1,2 rather than 2,1. That seems wrong to me.
>
> Changing it would probably break a thousand scripts. But could we have an additional option to respect the order of fields given on the command line? It is a pain to rearrange fields with sed, though of course it can be done.
>
> Thanks, and keep up the good work.
>
> James
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> --- Begin Message ---
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> Subject: 
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> Re: bug#9507: cut bug?
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> Date: 
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> Wed, 14 Sep 2011 10:52:45 -0600
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> User-agent: 
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> Mozilla/5.0 (X11; U; Linux x86_64; en-US;	rv:1.9.2.20) Gecko/20110831 Fedora/3.1.12-2.fc14	Lightning/1.0b3pre Mnenhy/0.8.3 Thunderbird/3.1.12
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> tag 9507 notabug
> merge 6394 9507
> thanks
>
> On 09/14/2011 10:20 AM, James Heather wrote:
> > Hi,
> >
> > I'm sure this must have been spotted before, but
> >
> >      cut -f2,1
> >
> > produces the fields in the order 1,2 rather than 2,1. That seems wrong
> > to me.
>
> You're not the first to complain of this, and probably won't be the last.
>
> > Changing it would probably break a thousand scripts.
>
> Yep.  And it would also violate POSIX, so changing it now is a 
> non-starter.  For reference, here's the POSIX text:
>
> http://pubs.opengroup.org/onlinepubs/9699919799/utilities/cut.html
>
> "The elements in list can be repeated, can overlap, and can be specified 
> in any order, but the bytes, characters, or fields selected shall be 
> written in the order of the input data."
>
> "The list option-arguments are historically used to select the portions 
> of the line to be written, but do not affect the order of the data. For 
> example:
>
> echo abcdefghi | cut -c6,2,4-7,1
>
> yields "abdefg"."
>
> > But could we have
> > an additional option to respect the order of fields given on the command
> > line?
>
> Why?  It's already portable to use awk:
>
> awk '{print $2,$1}'
>
> https://lists.gnu.org/archive/html/bug-coreutils/2007-09/msg00169.html
>
> at which point, you have the choice between a POSIX-mandated solution 
> already on your system, even if you don't use coreutils; or waiting for 
> a coreutils extension to be written and propagate to your distro, and 
> which still won't work on other platforms like BSD.  You can tell which 
> way we are leaning.
>
> > It is a pain to rearrange fields with sed, though of course it can
> > be done.
>
> awk is better than sed for this task.
>
> --
> Eric Blake   address@hidden    +1-801-349-2682
> Libvirt virtualization library http://libvirt.org
>
>
> --- End Message ---