Often one has files jan1, jan2, ..., jan9, jan10,
... and it feels wrong when ls orders them jan1, jan10,
..., jan2, ..., jan9. In order to rectify this, GNU introduced
the -v option to ls(1), which is implemented using
versionsort(3), which again uses strverscmp.
Thus, the task of strverscmp is to compare two strings and find the
"right" order, while strcmp only finds the lexicographic
order. This function does not use the locale category LC_COLLATE, so is meant
mostly for situations where the strings are expected to be in ASCII.
What this function does is the following. If both strings are equal, return 0.
Otherwise find the position between two bytes with the property that before it
both strings are equal, while directly after it there is a difference. Find
the largest consecutive digit strings containing (or starting at, or ending
at) this position. If one or both of these is empty, then return what
strcmp would have returned (numerical ordering of byte values).
Otherwise, compare both digit strings numerically, where digit strings with
one or more leading zeroes are interpreted as if they have a decimal point in
front (so that in particular digit strings with more leading zeroes come
before digit strings with fewer leading zeroes). Thus, the ordering is
000, 00, 01, 010, 09, 0, 1,