`sort' - is this a (minor) bug, or just an unexpected behavior ?!?

sort --version

sort (textutils) 2.0.14
Written by Mike Haertel and Paul Eggert.
[April 2001]


and, FWIW

uname -a

Linux 2.4.7-10 #1 Thu Sep 6 17:27:27 EDT 2001 i686 unknown



I read man and info pages, but didn't find an explanation for the facts
below :
[anyway, please, bear in mind that english is not my mother tongue]


Consider a four-line text file, referred here as `file_name', which is made
of the following lines :

5               6c
3               7c
1               9c
4               8c


sort -k 2,2 file_name

returns correctly

5               6c
3               7c
4               8c
1               9c


but

sort -k 2.1,2.1 file_name

(say I want to ignore char[s] past the numerical values, I know that's trivial,
but assume
I have a very long file to sort and using a one char only key, speeds it
up significately)

returns

1               9c
3               7c
4               8c
5               6c

that is, it sorts as if no key were given, using the entire line as the
key.

-------

the problem seems to be in the end delimiter of the key, as doing

sort -k 2.1,2 file_name


works as expected, returning


5               6c
3               7c
4               8c
1               9c


whereas

sort -k 2,2.1 file_name


returns the unexpected one

1               9c
3               7c
4               8c
5               6c


Hope this helps.

-------------------------------------------------

By the way, let me ask two related questions, whose answers I couldn't find
documented anywhere :


1) Sometimes I need to sort file using as key absolute char position, as
opposed to char
position relative to fields.

Say I want to sort a file using as unique key chars in columns 11 through
16
(Assume each line of the file has 25 or more chars)

I issue the following command

sort -k 1.11,1.16 other_file_name

and everything works, even if the first field has less than 11 chars, say
just 5 or 6)


[The same happens if I were to use two keys in place of one, say

sort -k 1.11,1.16 -k 1.21,1.23 other_file_name

]


Is that an undocumented feature, or just something which could stop working
with some next
release of `sort' (textutils) ?



2) What really happens when defining a key you express it in reverse order
?

e.g.

sort -k 8,3 file_name_another

that is reversing fields (I assume my file has at least 8 fields)

and

sort -k 2.6,2.3 file_name_another

that is reversing char position in a field (I assume second filed is at
least 6 chars long)



It seems that the sort is performed as if no key were given,
using the entire line as the key; but I'm not sure.


David Fabiani

[email protected]




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