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Re: sort's --key argument
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From: |
Eric Blake |
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Subject: |
Re: sort's --key argument |
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Date: |
Mon, 27 Jun 2011 13:31:59 -0600 |
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Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc14 Lightning/1.0b3pre Mnenhy/0.8.3 Thunderbird/3.1.10 |
On 06/27/2011 11:10 AM, Peng Yu wrote:
> Hi,
>
> I want to sort by the 2nd column (see the 2nd command). But it seems
> that it still sorts by the second column then by the first column.
> Does anybody know how --key works?
Yes. Unless you specify -s/--stable, then coreutils uses a last-resort
sort, as if you had specified -k1 for selecting the entire line. And
'sort --debug' shows this:
> $sort --key=2,2 input.txt
$ LC_ALL=C sort --debug -k2,2 input.txt
sort: using simple byte comparison
a a
__
___
p a
__
___
$ LC_ALL=C sort --debug -k2,2 input.txt -s
sort: using simple byte comparison
p a
__
a a
__
> sort (GNU coreutils) 7.4
Well, you won't get the --debug option unless you upgrade to newer
coreutils; it was added in 8.6 (latest is now 8.12).
--
Eric Blake address@hidden +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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