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Subject: |
sort manpage should be more explicit |
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Date: |
Thu, 28 Sep 2023 07:11:50 -0300 |
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User-agent: |
Horde Application Framework 5 |
The full documentation of sort explains that numeric sorting (as in
"sort -n") accepts a leading "-" sign, decimal points, thousands
separators, etc, but does not accept an explicit "+" sign. Values with
explicit "+" are treated as numeric 0 and ties are broken by alpha sort.
However, the manpage only says that "-n" "compares according to string
numerical value" -- and one would expect the numerical value of "+100"
to be 100, not zero.
It took me an hour to figure out that my "sort -n" was failing because
of this "feature". Surely many users have wasted time too, or worse.
So please either
1) explain precisely IN THE MANPAGE what is a valid number;
2) make numeric sort accept a leading "+", as users would expect;
3) make numeric sort abort with an error message if any field that is
supposed to be sorted numerically is not a valid number.
I think the best solution for users would be to implement all three of
these...
Thank you, and all the best
--jorge
--
Jorge Stolfi - Professor Titular/Full Professor
Instituto de Computação/Computer Science Dept
Universidade Estadual de Campinas/State University of Campinas
Campinas, SP - Brazil
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--- Begin Message ---
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Subject: |
Re: bug#66253: sort manpage should be more explicit |
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Date: |
Thu, 28 Sep 2023 12:22:35 +0100 |
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User-agent: |
Mozilla Thunderbird |
On 28/09/2023 11:11, Jorge Stolfi wrote:
The full documentation of sort explains that numeric sorting (as in
"sort -n") accepts a leading "-" sign, decimal points, thousands
separators, etc, but does not accept an explicit "+" sign. Values with
explicit "+" are treated as numeric 0 and ties are broken by alpha sort.
However, the manpage only says that "-n" "compares according to string
numerical value" -- and one would expect the numerical value of "+100"
to be 100, not zero.
It took me an hour to figure out that my "sort -n" was failing because
of this "feature". Surely many users have wasted time too, or worse.
So please either
1) explain precisely IN THE MANPAGE what is a valid number;
2) make numeric sort accept a leading "+", as users would expect;
3) make numeric sort abort with an error message if any field that is
supposed to be sorted numerically is not a valid number.
I think the best solution for users would be to implement all three of
these...
Thank you, and all the best
Note the --debug option really helps with all this:
$ printf '%s\n' '+4' ' 5' '-1,2.3' | sort -s -n --debug
sort: note numbers use ‘.’ as a decimal point in this locale
-1,2.3
______
+4
^ no match for key
5
_
In saying that, sorting numbers is such a common use case,
it's probably worth adding an extra couple of lines to the man page.
I think I'll apply the following later:
-n, --numeric-sort compare according to string numerical value.
leading blanks, negative sign, decimal point,
and thousands separators are supported.
cheers,
Pádraig
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