Considering the sort key: a, a01 and a02, if there's no trailing fields, the sort result looks like:
$ cat test1
a01
a
a02
$ sort test1
a
a01
a02
$
But if there are tailing fields, something goes strange:
$ cat test2
a01 7
a 12
a02 42
$ sort test2
a01 7
a02 42
a 12
$
Why does the key "a" fall from the top to the bottom of the sort result?
My sort version is "sort (GNU coreutils) 5.97".