Ubuntu
coreutils package

sort doesn't sort and uniq loses data for many non-Latin scripts on UTF-8 locales

Bug #1774857 reported by Miikka-Markus Alhonen on 2018-06-03

This bug affects 1 person

Affects		Status	Importance	Assigned to	Milestone
	coreutils (Ubuntu)	New	Undecided	Unassigned
	glibc (Ubuntu)	New	Undecided	Unassigned

Bug Description

I’ve found out that sort doesn’t sort strings for many non-Latin scripts at all if the locale you’re using is one of en_US.UTF-8, fr_FR.UTF-8 or fi_FI.UTF-8 (probably others, too, but these are the ones I have tested). For locales ”C” and ko_KR.UTF-8, things work as expected. Here’s a test case:

Open xterm, launch sort and input some lines of Syriac, Ethiopic, Korean, Japanese (Hiragana or Katakana, not Han) or Thai text repeating one of the lines twice. Here’s an example in Syriac:

ܡܠܬܐ
ܒܝܬܐ
ܒܪܢܫܐ
ܡܠܬܐ

Sort produces the following:

ܡܠܬܐ
ܒܝܬܐ
ܡܠܬܐ
ܒܪܢܫܐ

Here strings are ordered only according to their length but not characters. Even the two instances of the word ܡܠܬܐ are found on non-adjacent lines (1 and 3). The expected sort order based on Unicode points would be:

ܒܝܬܐ
ܒܪܢܫܐ
ܡܠܬܐ
ܡܠܬܐ

If you further pass sort’s output to uniq, it produces the following:

ܡܠܬܐ
ܒܪܢܫܐ

Here the word on line 2 ܒܝܬܐ is completely lost since, like sort, uniq seems to consider all Syriac strings of equal length as the same.

Although this issue affects locale, I think it is not a locale issue per se, since perl seems to handle similar cases expectedly. For instance, the following command produces the expected result:

perl -CDS -e 'use locale; use utf8; @str = ("ܡܠܬܐ", "ܒܝܬܐ", "ܒܪܢܫܐ", "ܡܠܬܐ"); foreach $i (sort @str) { print "$i\n"; }'

Curiously enough, codepoints in Plane 1 seem to count as two codepoints of the basic plane, so that if you sort | uniq the following (six codepoints of Syriac and three codepoints of Phoenician):

ܥܠܝܟܘܢ
𐤁𐤉𐤕

you get ”ܥܠܝܟܘܢ" as the result whereas ”𐤁𐤉𐤕” is lost. This is of course due to the UTF-8 representation of Plane 1 characters as two surrogate characters on the basic plane.

Also curiously, LTR scripts seem to conflate with each other and RTL scripts among themselves but not across the directionality line, so that if you sort | uniq the following (three codepoints each in Ethiopic, Hangul, Syriac, Hiragana and Thai):

ዘመን
스물셋
ܐܢܐ
わたし
ฟ้า

you are left with:

ܐܢܐ
ዘመን

That’s one line of Syriac and one line of Ethiopic; everything else was lost. This issue does not seem to affect most Indic scripts (Devanagari, Bengali, Telugu etc.) or Arabic. For CJK, things work as expected for the main Unicode block (4E00..9FFF) but not for Extension A (3400..4DBF, such as 㗖 or 㡘 or 㰋). For Greek, monotonic accents work fine but all polytonic letters are conflated (αὐλὸς and αὐλῆς conflate to αὐλῆς). For Hebrew, letters and vowel marks work fine but cantillation marks are conflated.

Description: Ubuntu 18.04 LTS
Release: 18.04

coreutils:
  Installed: 8.28-1ubuntu1
  Candidate: 8.28-1ubuntu1
  Version table:
*** 8.28-1ubuntu1 500
        500 http://mr.archive.ubuntu.com/ubuntu bionic/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: coreutils 8.28-1ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-22.24-generic 4.15.17
Uname: Linux 4.15.0-22-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.1
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sun Jun 3 10:13:06 2018
InstallationDate: Installed on 2017-02-13 (474 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=fi_FI.UTF-8
SHELL=/bin/bash
SourcePackage: coreutils
UpgradeStatus: Upgraded to bionic on 2018-05-31 (2 days ago)

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