I think I used to use "env LC_ALL=C". I like to set "all" the things and I'm also fond of the useless use of env...
This does run faster, but it's also important if you want a predictable order and to distinguish all strings like you would get if you implemented your own text sort naively.
From Googling just now:
"sort -u doesn't report unique lines, but one of each group of lines that have equal sorting order. So if you do want unique lines, you need a locale where characters are byte and all characters have different sorting order (which the C locale guarantees)."
This does run faster, but it's also important if you want a predictable order and to distinguish all strings like you would get if you implemented your own text sort naively.
From Googling just now: "sort -u doesn't report unique lines, but one of each group of lines that have equal sorting order. So if you do want unique lines, you need a locale where characters are byte and all characters have different sorting order (which the C locale guarantees)."