linux sort unexpected output

Question

I use sort file

ABC
AB-C
ABCDEFG-HI

I get

ABC
AB-C
ABCDEFG-HI

why does sort orders the string this way? how do I make it sort '-' alphabetically?

Please post the exact sort call you're using, you're likely doing it wrong. — DarkDust
– DarkDust, Commented Jun 30, 2011 at 8:09

DarkDust · Accepted Answer · 2011-06-30 08:50:49Z

5

The solution provided by @cnicutar is correct, but the reason needs explanation which is why I'm giving a new answer.

After the discussion with @cnicutar where in the end I suspected a bug in coreutils' sort I found that this sorting behavior is expected:

At that point sort appears broken because case is folded and punctuation is ignored because ‘en_US.UTF-8’ specifies this behavior.

So to sort, your input seems to be mapped as follows:

ABC -> ABC
AB-C -> ABC
ABCDEFG-HI -> ABCDEFGHI

If you want pure ASCII sorting, you need to call LC_ALL=C sort (temporarily set the locale to C when calling sort which means "standard" behavior without localization; you can also use POSIX instead of C).

On other Unixes this behavior seems to be different (tested on Mac OS X which userland tools are derived from FreeBSD), but LC_ALL=C sort should yield the same behavior across all POSIX systems.

edited Jun 30, 2011 at 8:50

answered Jun 30, 2011 at 8:44

DarkDust

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Comments

cnicutar · Accepted Answer · 2011-06-30 08:11:27Z

3

I remember this :)) try

[cnicutar@aiur ~]$ LANG=POSIX sort
ABC
AB-C
ABCDEFG-HI
AB-C
ABC
ABCDEFG-HI

Alternatively LANG=C should work.

answered Jun 30, 2011 at 8:11

cnicutar

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8 Comments

DarkDust Over a year ago

In no language setting should the AB-C appear in the middle (not even with EBCDIC), so I bet that this isn't the problem but instead the way user678070 is calling sort.

cnicutar Over a year ago

@DarkDust I just tried it with different LANGs. For en_US.utf8 it does what the op says (I had this problem before). Do a locale -a and pick some.

DarkDust Over a year ago

@cnicutar: I just tried it myself and I still get the correct sorting. And given that only ASCII characters are used, I very much doubt en_US.utf8 would result in this strange sorting as UTF-8 has ASCII as a subset. Do you get the "unsorted" output when using LANG=foobar ? If so, then your sort doesn't sort when it can't find the locale.

cnicutar Over a year ago

@DarkDust What coreutils version are you using ? What does echo $LANG say ? What does locale -a say ? If you try to use a locale that's unavailable it is ignored. Btw, "I very much doubt" regarding to what I just said I tested sounds a bit offensive, don't you think ?

cnicutar Over a year ago

@DarkDust Even if I reorder the words, with LANG=en_US.utf8 I still get the order of the OP. And locale -a shows I have it available.

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