coreutils: Version-sort ordering rules
30.2.1 Version-sort ordering rules
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The version sort ordering rules are:
1. The strings are compared from left to right.
2. First the initial part of each string consisting entirely of
non-digit bytes is determined.
A. These two parts (either of which may be empty) are compared
lexically. If a difference is found it is returned.
B. The lexical comparison is a lexicographic comparison of byte
strings, except that:
a. ASCII letters sort before other bytes.
b. A tilde sorts before anything, even an empty string.
3. Then the initial part of the remainder of each string that contains
all the leading digits is determined. The numerical values
represented by these two parts are compared, and any difference
found is returned as the result of the comparison.
A. For these purposes an empty string (which can only occur at
the end of one or both version strings being compared) counts
as zero.
B. Because the numerical value is used, non-identical strings can
compare equal. For example, ‘123’ compares equal to ‘00123’,
and the empty string compares equal to ‘0’.
4. These two steps (comparing and removing initial non-digit strings
and initial digit strings) are repeated until a difference is found
or both strings are exhausted.
Consider the version-sort comparison of two file names: ‘foo07.7z’
and ‘foo7a.7z’. The two strings will be broken down to the following
parts, and the parts compared respectively from each string:
foo vs foo (rule 2, non-digits)
07 vs 7 (rule 3, digits)
. vs a. (rule 2)
7 vs 7 (rule 3)
z vs z (rule 2)
Comparison flow based on above algorithm:
1. The first parts (‘foo’) are identical.
2. The second parts (‘07’ and ‘7’) are compared numerically, and
compare equal.
3. The third parts (‘.’ vs ‘a.’) are compared lexically by ASCII value
(rule 2.B).
4. The first byte of the first string (‘.’) is compared to the first
byte of the second string (‘a’).
5. Rule 2.B.a says letters sorts before non-letters. Hence, ‘a’ comes
before ‘.’.
6. The returned result is that ‘foo7a.7z’ comes before ‘foo07.7z’.
Result when using sort:
$ cat input3
foo07.7z
foo7a.7z
$ sort -V input3
foo7a.7z
foo07.7z
See ⇒Differences from Debian version sort for additional rules
that extend the Debian algorithm in Coreutils.
Info Catalog
coreutils: Version sort implementation
coreutils: Version sort is not the same as numeric sort