document sort -uf[r]

[jidanni]

Regarding sort:
`-f'
`--ignore-case'
     Fold lowercase characters into the equivalent uppercase characters
     when comparing so that, for example, `b' and `B' sort as equal.
     The `LC_CTYPE' locale determines character types.

OK, but also document this:
$ echo -e 'A\na'|sort -uf
A
$ echo -e 'A\na'|sort -ufr
A
$ echo -e 'A\na'|sort -urf
A
The man page doesn't say what to expect.