SHELL

uniq linux

# uniq command filters outputs to be unique. For example:
sort letters.txt 
a b b c c c 
sort letters.txt | uniq
a b c
sort dogs.txt | uniq -d # Only shows duplicated lines
b c

uniq command in linux

The uniq command can count and print the number of repeated lines.
Just like duplicate lines, we can filter unique lines (non-duplicate lines)
as well 
and can also ignore case sensitivity. 
We can skip fields and characters before comparing duplicate lines 
and also consider characters for filtering lines.