30.2.3 Punctuation Characters

Punctuation characters are sorted by ASCII order (rule 2.2).

$ touch    1.0.5_src.tar.gz    1.0_src.tar.gz

$ ls -v -1

Why is 1.0.5_src.tar.gz listed before 1.0_src.tar.gz ?

Based on the algorithm above, the strings are broken down into the following parts:

          1   vs  1               (rule 3, all digit characters)
          .   vs  .               (rule 2, all non-digit characters)
          0   vs  0               (rule 3)
          .   vs  _src.tar.gz     (rule 2)
          5   vs  empty string    (no more character in the file name)
_src.tar.gz   vs  empty string

The fourth parts (‘.’ and _src.tar.gz) are compared lexically by ASCII order. The character ‘.’ (ASCII value 46) is smaller than ‘_’ (ASCII value 95) - and should be listed before it.

Hence, 1.0.5_src.tar.gz is listed first.

If a different character appears instead of the underscore (for example, percent sign ‘%’ ASCII value 37, which is smaller than dot’s ASCII value of 46), that file will be listed first:

$ touch   1.0.5_src.tar.gz     1.0%zzzzz.gz

The same reasoning applies to the following example: The character ‘.’ has ASCII value 46, and is smaller than slash character ‘/’ ASCII value 47:

$ cat input5

$ sort -V input5