Subject: Re: bug#49503: Mention workarounds, so one could achieve the Debian version sorting algorithm

From: Paul Eggert <[email-masked]>
Date: Thu, 10 Feb 2022 11:07:37 -0800

On 7/10/21 02:23, 積丹尼 Dan Jacobson wrote:
> (info "(coreutils) Differences from the official Debian Algorithm") and
> (info "(coreutils) Minus/Hyphen and Colon characters")
> could mention workarounds, so one could indeed achieve the Debian
> Algorithm.
> Or mention the only way is to use
> dpkg --compare-versions
> (on pairs only.)

Thanks for mentioning that. I looked over the version-sort doc and fixed 
that problem along with some other stuff I noticed while in the 
neighborhood, by installing the attached patch.

From cedf627a901e067ad3a63f0fc20f3376ed59786e Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email-masked]>
Date: Tue, 8 Feb 2022 10:52:10 -0800
Subject: [PATCH] doc: improve version-sort doc
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* doc/coreutils.texi, doc/sort-version.texi:
Capitalize “Coreutils”.
* doc/sort-version.texi: Don’t emphasize natural sort so much,
since Coreutils has just version sort.
Use the term “lexicographic” instead of “alphabetic” or “standard”.
Suggest combining ‘V’ with ‘b’, and show why ‘b’ is needed.
Use shorter titles for sections, as GNU Emacs displays info poorly
when titles are too long to fit in a line.
Use @samp instead of @code for samples of data.
Do not use @samp{@code{...}}; @samp{...} should suffice and
double-nesting looks bad with Emacs.
Omit blank lines in examples that would not be present
in actual shell sessions.
Quote with `` and '', not with " or with '.
Mention dpkg --compare-versions more prominently.
Don’t rely on "\n" being equivalent to "\\n" in shell args.
Prefer Unicode name for hyphen-minus.
---
 doc/coreutils.texi    |  14 +-
 doc/sort-version.texi | 402 +++++++++++++++++++++---------------------
 2 files changed, 204 insertions(+), 212 deletions(-)

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 75b868219..d1ad85865 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -498,9 +498,9 @@ Date input formats
 Version sorting order
 
 * Version sort overview::
-* Implementation Details::
-* Differences from the official Debian Algorithm::
-* Advanced Topics::
+* Version sort implementation::
+* Differences from Debian version sort::
+* Advanced version sort topics::
 
 Opening the software toolbox
 
@@ -3991,7 +3991,7 @@ Output extra information to stderr, like the checksum implementation being used.
 
 @item --untagged
 @opindex --untagged
-Output using the original coreutils format used by the other
+Output using the original Coreutils format used by the other
 standalone checksum utilities like @command{md5sum} for example.
 This format has the checksum at the start of the line, and may be
 more amenable to further processing by other utilities,
@@ -13922,11 +13922,11 @@ If a file being written to does not already exist, it is created.  If a
 file being written to already exists, the data it previously contained
 is overwritten unless the @option{-a} option is used.
 
-In previous versions of GNU coreutils (v5.3.0 - v8.23), a @var{file} of @samp{-}
+In previous versions of GNU Coreutils (v5.3.0 -- v8.23),
+a @var{file} of @samp{-}
 caused @command{tee} to send another copy of input to standard output.
 However, as the interleaved output was not very useful, @command{tee} now
-conforms to POSIX which explicitly mandates it to treat @samp{-} as a file
-with such name.
+conforms to POSIX and treats @samp{-} as a file name.
 
 The program accepts the following options.  Also see @ref{Common options}.
 
diff --git a/doc/sort-version.texi b/doc/sort-version.texi
index 18ddaa94a..7f76ac5bb 100644
--- a/doc/sort-version.texi
+++ b/doc/sort-version.texi
@@ -19,18 +19,17 @@
 @node Version sort overview
 @section Version sort overview
 
-@dfn{version sort} ordering (and similarly, @dfn{natural sort}
-ordering) is a method to sort items such as file names and lines of
-text in an order that feels more natural to people, when the text
+@dfn{Version sort} puts items such as file names and lines of
+text in an order that feels natural to people, when the text
 contains a mixture of letters and digits.
 
-Standard sorting usually does not produce the order that one expects
+Lexicographic sorting usually does not produce the order that one expects
 because comparisons are made on a character-by-character basis.
 
 Compare the sorting of the following items:
 
 @example
-Alphabetical sort:           Version Sort:
+Lexicographic sort:          Version Sort:
 
 a1                           a1
 a120                         a2
@@ -38,18 +37,19 @@ a13                          a13
 a2                           a120
 @end example
 
-version sort functionality in GNU coreutils is available in the @samp{ls -v},
-@samp{ls --sort=version}, @samp{sort -V}, @samp{sort --version-sort} commands.
+Version sort functionality in GNU Coreutils is available in the @samp{ls -v},
+@samp{ls --sort=version}, @samp{sort -V}, and
+@samp{sort --version-sort} commands.

-@node Using version sort in GNU coreutils
-@subsection Using version sort in GNU coreutils
+@node Using version sort in GNU Coreutils
+@subsection Using version sort in GNU Coreutils
 
-Two GNU coreutils programs use version sort: @command{ls} and @command{sort}.
+Two GNU Coreutils programs use version sort: @command{ls} and @command{sort}.
 
 To list files in version sort order, use @command{ls}
-with @option{-v} or @option{--sort=version} options:
+with the @option{-v} or @option{--sort=version} option:
 
 @example
 default sort:              version sort:
@@ -64,7 +64,7 @@ a2                         a100
 @end example
 
 To sort text files in version sort order, use @command{sort} with
-the @option{-V} option:
+the @option{-V} or @option{--version-sort} option:
 
 @example
 $ cat input
@@ -74,7 +74,7 @@ b1
 b20

-alphabetical order:        version sort order:
+lexicographic order:       version sort order:
 
 $ sort input               $ sort -V input
 b1                         b1
@@ -83,71 +83,71 @@ b20                        b11
 b3                         b20
 @end example
 
-To sort a specific column in a file use @option{-k/--key} with @samp{V}
-ordering option:
+To sort a specific field in a file, use @option{-k/--key} with
+@samp{V} type sorting, which is often combined with @samp{b} to
+ignore leading blanks in the field:
 
 @example
 $ cat input2
-1000  b3   apples
+100   b3   apples
 2000  b11  oranges
 3000  b1   potatoes
 4000  b20  bananas
-
-$ sort -k2V,2 input2
+$ sort -k 2bV,2 input2
 3000  b1   potatoes
-1000  b3   apples
+100   b3   apples
 2000  b11  oranges
 4000  b20  bananas
 @end example
 
-@node Origin of version sort and differences from natural sort
-@subsection Origin of version sort and differences from natural sort
+@node Version sort and natural sort
+@subsection Version sort and natural sort
 
-In GNU coreutils, the name @dfn{version sort} was chosen because it is based
+In GNU Coreutils, the name @dfn{version sort} was chosen because it is based
 on Debian GNU/Linux's algorithm of sorting packages' versions.
 
-Its goal is to answer the question
-``which package is newer, @file{firefox-60.7.2} or @file{firefox-60.12.3} ?''
+Its goal is to answer questions like
+``Which package is newer, @file{firefox-60.7.2} or @file{firefox-60.12.3}?''
 
-In coreutils this algorithm was slightly modified to work on more
+In Coreutils this algorithm was slightly modified to work on more
 general input such as textual strings and file names
-(see @ref{Differences from the official Debian Algorithm}).
+(see @ref{Differences from Debian version sort}).
 
 In other contexts, such as other programs and other programming
 languages, a similar sorting functionality is called
 @uref{https://en.wikipedia.org/wiki/Natural_sort_order,natural sort}.

-@node Correct/Incorrect ordering and Expected/Unexpected results
-@subsection Correct/Incorrect ordering and Expected/Unexpected results
+@node Variations in version sort order
+@subsection Variations in version sort order
 
-Currently there is no standard for version/natural sort ordering.
+Currently there is no standard for version sort.
 
 That is: there is no one correct way or universally agreed-upon way to
 order items. Each program and each programming language can decide its
-own ordering algorithm and call it 'natural sort' (or other various
-names).
+own ordering algorithm and call it ``version sort'', ``natural sort'',
+or other names.
 
 See @ref{Other version/natural sort implementations} for many examples of
 differing sorting possibilities, each with its own rules and variations.
 
-If you do suspect a bug in coreutils' implementation of version-sort,
-see @ref{Reporting bugs or incorrect results} on how to report them.
+If you find a bug in the Coreutils implementation of version-sort, please
+report it.  @xref{Reporting version sort bugs}.

-@node Implementation Details
-@section Implementation Details
+@node Version sort implementation
+@section Version sort implementation
 
-GNU coreutils' version sort algorithm is based on
+GNU Coreutils version sort is based on the ``upstream version''
+part of
 @uref{https://www.debian.org/doc/debian-policy/ch-controlfields.html#version,
-Debian's versioning scheme}, specifically on the "upstream version"
-part.
+Debian's versioning scheme}.
 
-This section describes the ordering rules.
+This section describes the GNU Coreutils sort ordering rules.
 
-The next section (@ref{Differences from the official Debian
-Algorithm}) describes some differences between GNU coreutils
-implementation and Debian's official algorithm.
+The next section (@ref{Differences from Debian version
+sort}) describes some differences between GNU Coreutils
+and Debian version sort.

 @node Version-sort ordering rules
@@ -173,9 +173,9 @@ The lexical comparison is a comparison of ASCII values modified so that:
 
 @enumerate
 @item
-all the letters sort earlier than all the non-letters and
+Letters sort before non-letters.
 @item
-so that a tilde sorts before anything, even the end of a part.
+A tilde sorts before anything, even the end of a part.
 @end enumerate
 @end enumerate
 
@@ -202,8 +202,8 @@ down to the following parts, and the parts compared respectively from
 each string:
 
 @example
-foo  @r{vs}  foo   @r{(rule 2, non-digits characters)}
-07   @r{vs}  7     @r{(rule 3, digits characters)}
+foo  @r{vs}  foo   @r{(rule 2, non-digit characters)}
+07   @r{vs}  7     @r{(rule 3, digits)}
 .    @r{vs}  a.    @r{(rule 2)}
 7    @r{vs}  7     @r{(rule 3)}
 z    @r{vs}  z     @r{(rule 2)}
@@ -213,23 +213,23 @@ Comparison flow based on above algorithm:
 
 @enumerate
 @item
-The first parts (@code{foo}) are identical in both strings.
+The first parts (@samp{foo}) are identical in both strings.
 
 @item
-The second parts (@code{07} and @code{7}) are compared numerically,
+The second parts (@samp{07} and @samp{7}) are compared numerically,
 and are identical.
 
 @item
-The third parts (@samp{@code{.}} vs @samp{@code{a.}}) are compared
+The third parts (@samp{.} vs @samp{a.}) are compared
 lexically by ASCII value (rule 2.2).
 
 @item
-The first character of the first string (@samp{@code{.}}) is compared
-to the first character of the second string (@samp{@code{a}}).
+The first character of the first string (@samp{.}) is compared
+to the first character of the second string (@samp{a}).
 
 @item
-Rule 2.2.1 dictates that "all letters sorts earlier than all non-letters".
-Hence, @samp{@code{a}} comes before @samp{@code{.}}.
+Rule 2.2.1 dictates that ``all letters sorts earlier than all non-letters''.
+Hence, @samp{a} comes before @samp{.}.
 
 @item
 The returned result is that @file{foo7a.7z} comes before @file{foo07.7z}.
@@ -241,14 +241,13 @@ Result when using sort:
 $ cat input3
 foo07.7z
 foo7a.7z
-
 $ sort -V input3
 foo7a.7z
 foo07.7z
 @end example
 
-See @ref{Differences from the official Debian Algorithm} for
-additional rules that extend the Debian algorithm in coreutils.
+See @ref{Differences from Debian version sort} for
+additional rules that extend the Debian algorithm in Coreutils.

 @node Version sort is not the same as numeric sort
@@ -266,8 +265,6 @@ $ cat input4
 8.100
 8.49
 
-
-
 Numerical Sort:                   Version Sort:
 
 $ sort -n input4                  $ sort -V input4
@@ -281,46 +278,45 @@ $ sort -n input4                  $ sort -V input4
 @end example
 
 Numeric sort (@samp{sort -n}) treats the entire string as a single numeric
-value, and compares it to other values. For example, @code{8.1}, @code{8.10} and
-@code{8.100} are numerically equivalent, and are ordered together. Similarly,
-@code{8.49} is numerically smaller than @code{8.5}, and appears before first.
+value, and compares it to other values. For example, @samp{8.1}, @samp{8.10} and
+@samp{8.100} are numerically equivalent, and are ordered together. Similarly,
+@samp{8.49} is numerically smaller than @samp{8.5}, and appears before first.
 
-Version sort (@samp{sort -V}) first breaks down the string into digits and
-non-digits parts, and only then compares each part (see annotated
+Version sort (@samp{sort -V}) first breaks down the string into digit and
+non-digit parts, and only then compares each part (see annotated
 example in Version-sort ordering rules).
 
-Comparing the string @code{8.1} to @code{8.01}, first the
-@samp{@code{8}} characters are compared (and are identical), then the
-dots (@samp{@code{.}}) are compared and are identical, and lastly the
-remaining digits are compared numerically (@code{1} and @code{01}) -
-which are numerically equivalent. Hence, @code{8.01} and @code{8.1}
+Comparing the string @samp{8.1} to @samp{8.01}, first the
+@samp{8} characters are compared (and are identical), then the
+dots (@samp{.}) are compared and are identical, and lastly the
+remaining digits are compared numerically (@samp{1} and @samp{01}) -
+which are numerically equivalent. Hence, @samp{8.01} and @samp{8.1}
 are grouped together.
 
-Similarly, comparing @code{8.5} to @code{8.49} - the @samp{@code{8}}
-and @samp{@code{.}} parts are identical, then the numeric values @code{5} and
-@code{49} are compared. The resulting @code{5} appears before @code{49}.
+Similarly, comparing @samp{8.5} to @samp{8.49} -- the @samp{8}
+and @samp{.} parts are identical, then the numeric values @samp{5} and
+@samp{49} are compared. The resulting @samp{5} appears before @samp{49}.
 
-This sorting order (where @code{8.5} comes before @code{8.49}) is common when
+This sorting order (where @samp{8.5} comes before @samp{8.49}) is common when
 assigning versions to computer programs (while perhaps not intuitive
-or 'natural' for people).
+or ``natural'' for people).
 
-@node Punctuation Characters
-@subsection Punctuation Characters
+@node Punctuation characters
+@subsection Punctuation characters
 
 Punctuation characters are sorted by ASCII order (rule 2.2).
 
 @example
-$ touch    1.0.5_src.tar.gz    1.0_src.tar.gz
-
+$ touch 1.0.5_src.tar.gz 1.0_src.tar.gz
 $ ls -v -1
 1.0.5_src.tar.gz
 1.0_src.tar.gz
 @end example
 
-Why is @file{1.0.5_src.tar.gz} listed before @file{1.0_src.tar.gz} ?
+Why is @file{1.0.5_src.tar.gz} listed before @file{1.0_src.tar.gz}?
 
-Based on the @ref{Version-sort ordering rules,algorithm,algorithm}
-above, the strings are broken down into the following parts:
+Based on the version-sort ordering rules, the strings are broken down
+into the following parts:
 
 @example
           1   @r{vs}  1               @r{(rule 3, all digit characters)}
@@ -331,14 +327,14 @@ above, the strings are broken down into the following parts:
 _src.tar.gz   @r{vs}  empty string
 @end example
 
-The fourth parts (@samp{@code{.}} and @code{_src.tar.gz}) are compared
-lexically by ASCII order. The character @samp{@code{.}} (ASCII value 46) is
-smaller than @samp{@code{_}} (ASCII value 95) - and should be listed before it.
+The fourth parts (@samp{.} and @samp{_src.tar.gz}) are compared
+lexically by ASCII order. The character @samp{.} (ASCII value 46) is
+smaller than @samp{_} (ASCII value 95) -- and should be listed before it.
 
 Hence, @file{1.0.5_src.tar.gz} is listed first.
 
 If a different character appears instead of the underscore (for
-example, percent sign @samp{@code{%}} ASCII value 37, which is smaller
+example, percent sign @samp{%} ASCII value 37, which is smaller
 than dot's ASCII value of 46), that file will be listed first:
 
 @example
@@ -347,32 +343,29 @@ $ touch   1.0.5_src.tar.gz     1.0%zzzzz.gz
 1.0.5_src.tar.gz
 @end example
 
-The same reasoning applies to the following example: The character
-@samp{@code{.}}  has ASCII value 46, and is smaller than slash
-character @samp{@code{/}} ASCII value 47:
+The same reasoning applies to the following example, as @samp{.} with
+ASCII value 46 is smaller than @samp{/} with ASCII value 47:
 
 @example
 $ cat input5
 3.0/
 3.0.5
-
 $ sort -V input5
 3.0.5
 3.0/
 @end example

-@node Punctuation Characters vs letters
-@subsection Punctuation Characters vs letters
+@node Punctuation vs letters
+@subsection Punctuation vs letters
 
 Rule 2.2.1 dictates that letters sorts earlier than all non-letters
-(after breaking down a string to digits and non-digits parts).
+(after breaking down a string to digit and non-digit parts).
 
 @example
 $ cat input6
 a%
 az
-
 $ sort -V input6
 az
 a%
@@ -380,21 +373,21 @@ a%
 
 The input strings consist entirely of non-digits, and based on the
 above algorithm have only one part, all non-digit characters
-(@samp{@code{a%}} vs @samp{@code{az}}).
+(@samp{a%} vs @samp{az}).
 
 Each part is then compared lexically,
-character-by-character. @samp{@code{a}} compares identically in both
+character-by-character. @samp{a} compares identically in both
 strings.
 
-Rule 2.2.1 dictates that letters (@samp{@code{z}}) sorts earlier than all
-non-letters (@samp{@code{%}}) - hence @samp{@code{az}} appears first (despite
-@samp{@code{z}} having ASCII value of 122, much bigger than @samp{@code{%}}
+Rule 2.2.1 dictates that letters (@samp{z}) sorts earlier than all
+non-letters (@samp{%}) -- hence @samp{az} appears first (despite
+@samp{z} having ASCII value of 122, much larger than @samp{%}
 with ASCII value 37).
 
-@node Tilde @samp{~} character
-@subsection Tilde @samp{~} character
+@node The tilde @samp{~} character
+@subsection The tilde @samp{~} character
 
-Rule 2.2.2 dictates that tilde character @samp{@code{~}} (ASCII 126) sorts
+Rule 2.2.2 dictates that the tilde character @samp{~} (ASCII 126) sorts
 before all other non-digit characters, including an empty part.
 
 @example
@@ -404,7 +397,6 @@ $ cat input7
 1.2
 1~
 ~
-
 $ sort -V input7
 ~
 1~
@@ -414,42 +406,42 @@ $ sort -V input7
 @end example
 
 The sorting algorithm starts by breaking down the string into
-non-digits (rule 2) and digits parts (rule 3).
+non-digit (rule 2) and digit parts (rule 3).
 
 In the above input file, only the last line in the input file starts
-with a non-digit (@samp{@code{~}}). This is the first part. All other lines
-in the input file start with a digit - their first non-digit part is
+with a non-digit (@samp{~}). This is the first part. All other lines
+in the input file start with a digit -- their first non-digit part is
 empty.
 
-Based on rule 2.2.2, tilde @samp{@code{~}} sorts before all other non-digits
-including the empty part - hence it comes before all other strings,
+Based on rule 2.2.2, tilde @samp{~} sorts before all other non-digits
+including the empty part -- hence it comes before all other strings,
 and is listed first in the sorted output.
 
-The remaining lines (@code{1}, @code{1%}, @code{1.2}, @code{1~})
+The remaining lines (@samp{1}, @samp{1%}, @samp{1.2}, @samp{1~})
 follow similar logic: The digit part is extracted (1 for all strings)
 and compares identical. The following extracted parts for the remaining
-input lines are: empty part, @code{%}, @code{.}, @code{~}.
+input lines are: empty part, @samp{%}, @samp{.}, @samp{~}.
 
-Tilde sorts before all others, hence the line @code{1~} appears next.
+Tilde sorts before all others, hence the line @samp{1~} appears next.
 
-The remaining lines (@code{1}, @code{1%}, @code{1.2}) are sorted based
+The remaining lines (@samp{1}, @samp{1%}, @samp{1.2}) are sorted based
 on previously explained rules.
 
 @node Version sort ignores locale
-@subsection Version sort uses ASCII order, ignores locale, unicode characters
+@subsection Version sort ignores locale
 
-In version sort, unicode characters are compared byte-by-byte according
-to their binary representation, ignoring their unicode value or the
+In version sort, Unicode characters are compared byte-by-byte according
+to their binary representation, ignoring their Unicode value or the
 current locale.
 
-Most commonly, unicode characters (e.g. Greek Small Letter Alpha
-U+03B1 @samp{α}) are encoded as UTF-8 bytes (e.g. @samp{α} is encoded as UTF-8
-sequence @code{0xCE 0xB1}). The encoding will be compared byte-by-byte,
-e.g. first @code{0xCE} (decimal value 206) then @code{0xB1} (decimal value 177).
+Most commonly, Unicode characters are encoded as UTF-8 bytes; for
+example, GREEK SMALL LETTER ALPHA (U+03B1, @samp{α}) is encoded as the
+UTF-8 sequence @samp{0xCE 0xB1}).  The encoding is compared
+byte-by-byte, e.g., first @samp{0xCE} (decimal value 206) then
+@samp{0xB1} (decimal value 177).
 
 @example
-$ touch   aa    az    "a%"    "aα"
-
+$ touch aa az "a%" "aα"
 $ ls -1 -v
 aa
 az
@@ -457,32 +449,32 @@ a%
 aα
 @end example
 
-Ignoring the first letter (@code{a}) which is identical in all
+Ignoring the first letter (@samp{a}) which is identical in all
 strings, the compared values are:
 
-@samp{@code{a}} and @samp{@code{z}} are letters, and sort earlier than
+@samp{a} and @samp{z} are letters, and sort earlier than
 all other non-digit characters.
 
-Then, percent sign @samp{@code{%}} (ASCII value 37) is compared to the
-first byte of the UTF-8 sequence of @samp{@code{α}}, which is 0xCE or 206). The
-value 37 is smaller, hence @samp{@code{a%}} is listed before @samp{@code{aα}}.
+Then, percent sign @samp{%} (ASCII value 37) is compared to the
+first byte of the UTF-8 sequence of @samp{α}, which is 0xCE or 206). The
+value 37 is smaller, hence @samp{a%} is listed before @samp{aα}.
 
-@node Differences from the official Debian Algorithm
-@section Differences from the official Debian Algorithm
+@node Differences from Debian version sort
+@section Differences from Debian version sort
 
-The GNU coreutils' version sort algorithm differs slightly from the
+GNU Coreutils version sort differs slightly from the
 official Debian algorithm, in order to accommodate more general usage
 and file name listing.

-@node Minus/Hyphen and Colon characters
-@subsection Minus/Hyphen @samp{-} and Colon @samp{:} characters
+@node Hyphen-minus and colon characters
+@subsection Hyphen-minus @samp{-} and colon @samp{:} characters
 
 In Debian's version string syntax the version consists of three parts:
 @example
 [epoch:]upstream_version[-debian_revision]
 @end example
-The @code{epoch} and @code{debian_revision} parts are optional.
+The @samp{epoch} and @samp{debian_revision} parts are optional.
 
 Example of such version strings:
 
@@ -495,61 +487,63 @@ Example of such version strings:
 2:1.19.2-1+deb9u5
 @end example
 
-If the @code{debian_revision part} is not present,
+If the @samp{debian_revision part} is not present,
 hyphen characters @samp{-} are not allowed.
 If epoch is not present, colons @samp{:} are not allowed.
 
 If these parts are present, hyphen and/or colons can appear only once
 in valid Debian version strings.
 
-In GNU coreutils, such restrictions are not reasonable (a file name can
+In GNU Coreutils, such restrictions are not reasonable (a file name can
 have many hyphens, a line of text can have many colons).
 
-As a result, in GNU coreutils hyphens and colons are treated exactly
-like all other punctuation characters (i.e., they are sorted after
-letters. See Punctuation Characters above).
+As a result, in GNU Coreutils hyphens and colons are treated exactly
+like all other punctuation characters, i.e., they are sorted after
+letters.  @xref{Punctuation characters}.
 
-In Debian, these characters are treated differently than in coreutils:
+In Debian, these characters are treated differently than in Coreutils:
 a version string with hyphen will sort before similar strings without
 hyphens.
 
 Compare:
 
 @example
-$ touch   abb   ab-cd
-
+$ touch 1ab-cd 1abb
 $ ls -v -1
-abb
-ab-cd
+1abb
+1ab-cd
+$ if dpkg --compare-versions 1abb lt 1ab-cd
+> then echo sorted
+> else echo out of order
+> fi
+out of order
 @end example
 
-With Debian's @command{dpkg} they will be listed as @code{ab-cd} first and
-@code{abb} second.
-
-For further technical details see @uref{https://bugs.gnu.org/35939,bug35939}.
+For further details, see @ref{Comparing two strings using Debian's
+algorithm} and @uref{https://bugs.gnu.org/35939,GNU Bug 35939}.
 
-@node Additional hard-coded priorities in GNU coreutils' version sort
-@subsection Additional hard-coded priorities in GNU coreutils' version sort
+@node Additional hard-coded priorities in GNU Coreutils version sort
+@subsection Additional hard-coded priorities in GNU Coreutils version sort
 
-In GNU coreutils' version sort algorithm, the following items have
+In GNU Coreutils version sort, the following items have
 special priority and sort earlier than all other characters (listed in
 order);
 
 @enumerate
 @item The empty string
 
-@item The string @samp{@code{.}} (a single dot character, ASCII 46)
+@item The string @samp{.} (a single dot character, ASCII 46)
 
-@item The string @samp{@code{..}} (two dot characters)
+@item The string @samp{..} (two dot characters)
 
-@item Strings start with a dot (@samp{@code{.}}) sort earlier than
+@item Strings start with a dot (@samp{.}) sort earlier than
 strings starting with any other characters.
 @end enumerate
 
 Example:
 
 @example
-$ printf "%s\n" a "" b "." c  ".."  ".d20" ".d3"  | sort -V
+$ printf '%s\n' a "" b "." c  ".."  ".d20" ".d3"  | sort -V
 
 .
 ..
@@ -561,7 +555,7 @@ c
 @end example
 
 These priorities make perfect sense for @samp{ls -v}: The special
-files dot @samp{@code{.}} and dot-dot @samp{@code{..}} will be listed
+files dot @samp{.} and dot-dot @samp{..} will be listed
 first, followed by any hidden files (files starting with a dot),
 followed by non-hidden files.
 
@@ -572,7 +566,7 @@ program, the ordering rules are the same.
 @node Special handling of file extensions
 @subsection Special handling of file extensions
 
-GNU coreutils' version sort algorithm implements specialized handling
+GNU Coreutils version sort implements specialized handling
 of file extensions (or strings that look like file names with
 extensions).
 
@@ -606,37 +600,37 @@ Examples for rule 1:
 
 @itemize
 @item
-@code{hello-8.txt}: the suffix is @code{.txt}
+@samp{hello-8.txt}: the suffix is @samp{.txt}
 
 @item
-@code{hello-8.2.txt}: the suffix is @code{.txt}
-(@samp{@code{.2}} is not included because the dot is not followed by a letter)
+@samp{hello-8.2.txt}: the suffix is @samp{.txt}
+(@samp{.2} is not included because the dot is not followed by a letter)
 
 @item
-@code{hello-8.0.12.tar.gz}: the suffix is @code{.tar.gz} (@samp{@code{.0.12}}
+@samp{hello-8.0.12.tar.gz}: the suffix is @samp{.tar.gz} (@samp{.0.12}
 is not included)
 
 @item
-@code{hello-8.2}: no suffix (suffix is an empty string)
+@samp{hello-8.2}: no suffix (suffix is an empty string)
 
 @item
-@code{hello.foobar65}: the suffix is @code{.foobar65}
+@samp{hello.foobar65}: the suffix is @samp{.foobar65}
 
 @item
-@code{gcc-c++-10.8.12-0.7rc2.fc9.tar.bz2}: the suffix is
-@code{.fc9.tar.bz2} (@code{.7rc2} is not included as it begins with a digit)
+@samp{gcc-c++-10.8.12-0.7rc2.fc9.tar.bz2}: the suffix is
+@samp{.fc9.tar.bz2} (@samp{.7rc2} is not included as it begins with a digit)
 @end itemize
 
 Examples for rule 2:
 
 @itemize
 @item
-Comparing @code{hello-8.txt} to @code{hello-8.2.12.txt}, the
-@code{.txt} suffix is temporarily removed from both strings.
+Comparing @samp{hello-8.txt} to @samp{hello-8.2.12.txt}, the
+@samp{.txt} suffix is temporarily removed from both strings.
 
 @item
-Comparing @code{foo-10.3.tar.gz} to @code{foo-10.tar.xz}, the suffixes
-@code{.tar.gz} and @code{.tar.xz} are temporarily removed from the
+Comparing @samp{foo-10.3.tar.gz} to @samp{foo-10.tar.xz}, the suffixes
+@samp{.tar.gz} and @samp{.tar.xz} are temporarily removed from the
 strings.
 @end itemize
 
@@ -644,10 +638,10 @@ Example for rule 3:
 
 @itemize
 @item
-Comparing @code{hello.foobar65} to @code{hello.foobar4}, the suffixes
-(@code{.foobar65} and @code{.foobar4}) are temporarily removed. The
-remaining strings are identical (@code{hello}). The suffixes are then
-restored, and the entire strings are compared (@code{hello.foobar4} comes
+Comparing @samp{hello.foobar65} to @samp{hello.foobar4}, the suffixes
+(@samp{.foobar65} and @samp{.foobar4}) are temporarily removed. The
+remaining strings are identical (@samp{hello}). The suffixes are then
+restored, and the entire strings are compared (@samp{hello.foobar4} comes
 first).
 @end itemize
 
@@ -655,10 +649,10 @@ Examples for rule 4:
 
 @itemize
 @item
-When comparing the strings @code{hello-8.2.txt} and @code{hello-8.10.txt}, the
-suffixes (@code{.txt}) are temporarily removed. The remaining strings
-(@code{hello-8.2} and @code{hello-8.10}) are compared as previously described
-(@code{hello-8.2} comes first).
+When comparing the strings @samp{hello-8.2.txt} and @samp{hello-8.10.txt}, the
+suffixes (@samp{.txt}) are temporarily removed. The remaining strings
+(@samp{hello-8.2} and @samp{hello-8.10}) are compared as previously described
+(@samp{hello-8.2} comes first).
 @slanted{(In this case the suffix removal algorithm
 does not have a noticeable effect on the resulting order.)}
 @end itemize
@@ -678,8 +672,8 @@ empty   @r{vs}  2
 empty   @r{vs}  .txt
 @end example
 
-The comparison of the third parts (@samp{@code{.}} vs
-@samp{@code{.txt}}) will determine that the shorter string comes first -
+The comparison of the third parts (@samp{.} vs
+@samp{.txt}) will determine that the shorter string comes first -
 resulting in @file{hello-8.2.txt} appearing first.
 
 Indeed this is the order in which Debian's @command{dpkg} compares the strings.
@@ -687,7 +681,7 @@ Indeed this is the order in which Debian's @command{dpkg} compares the strings.
 A more natural result is that @file{hello-8.txt} should come before
 @file{hello-8.2.txt}, and this is where the suffix-removal comes into play:
 
-The suffixes (@code{.txt}) are removed, and the remaining strings are
+The suffixes (@samp{.txt}) are removed, and the remaining strings are
 broken down into the following parts:
 
 @example
@@ -697,7 +691,7 @@ empty   @r{vs}  .       @r{(rule 2)}
 empty   @r{vs}  2
 @end example
 
-As empty strings sort before non-empty strings, the result is @code{hello-8}
+As empty strings sort before non-empty strings, the result is @samp{hello-8}
 being first.
 
 A real-world example would be listing files such as:
@@ -714,10 +708,6 @@ because the sorting code is shared between the @command{ls} and @command{sort}
 program, the ordering rules are the same.

-@node Advanced Topics
-@section Advanced Topics
-
-
 @node Comparing two strings using Debian's algorithm
 @subsection Comparing two strings using Debian's algorithm
 
@@ -730,13 +720,14 @@ following snippet to your shell command-prompt):
 
 @example
 compver() @{
-  dpkg --compare-versions "$1" lt "$2" \
-    && printf "%s\n" "$1" "$2" \
-    || printf "%s\n" "$2" "$1" ; \
+  if dpkg --compare-versions "$1" lt "$2"
+  then printf '%s\n' "$1" "$2"
+  else printf '%s\n' "$2" "$1"
+  fi
 @}
 @end example
 
-Then compare two strings by calling compver:
+Then compare two strings by calling @command{compver}:
 
 @example
 $ compver 8.49 8.5
@@ -754,7 +745,6 @@ dpkg: warning: version 'foo7a.7z' has bad syntax:
                version number does not start with digit
 foo7a.7z
 foo07.7z
-
 $ compver "3.0/" "3.0.5"
 dpkg: warning: version '3.0/' has bad syntax:
                invalid character in version number
@@ -763,11 +753,11 @@ dpkg: warning: version '3.0/' has bad syntax:
 @end example
 
 To illustrate the different handling of hyphens between Debian and
-coreutils' algorithms (see
-@ref{Minus/Hyphen and Colon characters}):
+Coreutils algorithms (see
+@ref{Hyphen-minus and colon characters}):
 
 @example
-$ compver abb ab-cd 2>/dev/null     $ printf "abb\nab-cd\n" | sort -V
+$ compver abb ab-cd 2>/dev/null     $ printf 'abb\nab-cd\n' | sort -V
 ab-cd                               abb
 abb                                 ab-cd
 @end example
@@ -779,30 +769,32 @@ handling of file extensions}):
 $ compver hello-8.txt hello-8.2.txt 2>/dev/null
 hello-8.2.txt
 hello-8.txt
-
-$ printf "%s\n" hello-8.txt hello-8.2.txt | sort -V
+$ printf '%s\n' hello-8.txt hello-8.2.txt | sort -V
 hello-8.txt
 hello-8.2.txt
 @end example

+@node Advanced version sort topics
+@section Advanced Topics
+
 
-@node Reporting bugs or incorrect results
-@subsection Reporting bugs or incorrect results
+@node Reporting version sort bugs
+@subsection Reporting version sort bugs
 
-If you suspect a bug in GNU coreutils' version sort (i.e., in the
+If you suspect a bug in GNU Coreutils version sort (i.e., in the
 output of @samp{ls -v} or @samp{sort -V}), please first check the following:
 
 @enumerate
 @item
 Is the result consistent with Debian's own ordering (using @command{dpkg}, see
-@ref{Comparing two strings using Debian's algorithm}) ? If it is, then this
-is not a bug - please do not report it.
+@ref{Comparing two strings using Debian's algorithm})? If it is, then this
+is not a bug -- please do not report it.
 
 @item
 If the result differs from Debian's, is it explained by one of the
-sections in @ref{Differences from the official Debian Algorithm}? If it is,
-then this is not a bug - please do not report it.
+sections in @ref{Differences from Debian version sort}? If it is,
+then this is not a bug -- please do not report it.
 
 @item
 If you have a question about specific ordering which is not explained
@@ -833,7 +825,7 @@ Natural Sorting variants in
 Python's @uref{https://pypi.org/project/natsort/,natsort package}
 (includes detailed description of their sorting rules:
 @uref{https://natsort.readthedocs.io/en/master/howitworks.html,
-natsort - how it works}).
+natsort -- how it works}).
 
 @item
 Ruby's @uref{https://github.com/github/version_sorter,version_sorter}.
@@ -855,16 +847,16 @@ NodeJS's @uref{https://www.npmjs.com/package/natural-sort,natural-sort package}.
 @item
 In zsh, the
 @uref{http://zsh.sourceforge.net/Doc/Release/Expansion.html#Glob-Qualifiers,
-glob modifier} @code{*(n)} will expand to files in natural sort order.
+glob modifier} @samp{*(n)} will expand to files in natural sort order.
 
 @item
-When writing @code{C} programs, the GNU libc library (@code{glibc})
+When writing C programs, the GNU libc library (@samp{glibc})
 provides the
 @uref{http://man7.org/linux/man-pages/man3/strverscmp.3.html,
 strvercmp(3)} function to compare two strings, and
 @uref{http://man7.org/linux/man-pages/man3/versionsort.3.html,versionsort(3)}
 function to compare two directory entries (despite the names, they are
-not identical to GNU coreutils' version sort ordering).
+not identical to GNU Coreutils version sort ordering).
 
 @item
 Using Debian's sorting algorithm in:
@@ -882,8 +874,8 @@ deb-version-compare}.
 @end itemize

-@node Related Source code
-@subsection Related Source code
+@node Related source code
+@subsection Related source code
 
 @itemize
 
@@ -899,7 +891,7 @@ Debian's code which performs the @code{upstream_version} comparison:
 version.c}.
 
 @item
-GNULIB code (used by GNU coreutils) which performs the version comparison:
+Gnulib code (used by GNU Coreutils) which performs the version comparison:
 @uref{https://git.savannah.gnu.org/cgit/gnulib.git/tree/lib/filevercmp.c,
 filevercmp.c}.
 @end itemize
-- 
2.32.0