perl -ne 'push @a, $_; $h{$_}++; END{print grep {not --$h{$_}} @a}' file



##</code><code>##

    cabbage
    apple
    banana
    grape
    pear
    banana
    carrot
    apple
    apple
    banana
    grape
    pear
    banana
    apple

##</code><code>##

    cabbage
    carrot
    grape
    pear
    banana
    apple

##</code><code>##

    perl -ne 'print unless $h{$_}++' file

##</code><code>##

    sort -u file
    sort file | uniq