sort with tab field separator
Amadeus W.M.
amadeus84 at verizon.net
Sat Mar 22 23:49:10 UTC 2008
On Sat, 22 Mar 2008 23:06:54 +0000, Nicholas Robinson wrote:
> On Saturday 22 March 2008 21:38:46 Nicholas Robinson wrote:
>> On Saturday 22 March 2008 21:18:11 Amadeus W.M. wrote:
>> > You would think specifying tab as a field separator for sort would
>> > work like this:
>> >
>> > cat file | sort -k 3 -t "\t"
>> >
>> > It doesn't:
>> >
>> > sort: multi-character tab `\\t'
>> >
>> >
>> > So after a little search and some trial and error I got this to work:
>> >
>> > cat file | sort -k 3 -t "`/bin/echo -e '\t'`"
>> >
>> >
>> > For my own curiosity, can someone please illuminate me as to why the
>> > first incantation does not work as expected? Is there a more natural
>> > way to specify \t other than echo?
>>
>> Take the double quotes out in your first attempt. So command becomes
>>
>> cat file | sort -k 3 -t \t
>>
>> Nick
>
> Sorry, I was a little bit quick off the mark. The \t doesn't yield a tab
> character (see below) as you were implying and I went along with in the
> first example! If you take the double quotes out as I suggested, then
> the field separator becomes the character t!
>
> I think (being a little more cautious this time!) that you want:
>
> \ followed by Ctrl V followed by Ctrl I
>
> If I remember correctly, sort interprets a tab as a default field
> separator anyway.
>
> As to the why: it is because the -t takes an argument which is a
> character. Putting double quotes around it stops the \ being elided and
> so \t as two characters \ and t are presented to sort which is expecting
> only one character. Hence its moan. Try echo "\t" and you will see what
> I mean.
>
> In my second attempt above, the Ctrl V stops the tab character (Ctrl I)
> being expanded on the command line and the \ joins the tab character to
> the t.
>
> HTH
>
> Nick
Thank you!
How do I know Ctrl-V + Ctrl-I is \t?
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