Hello,
I wish to remove lines which appear twice in a file, actually
only when they appear more than one time.
How can I do so?
Do you need to keep the lines in the same order? If not, then
"sort -u" should work. You may also want to use "uniq".
% cat nonuniq.txt
dd
aa
bb
cc
bb
aa
% sort -u nonuniq.txt
aa
bb
cc
dd
--