uniq command in linux

uniq command: The uniq command is use to find  uniq value in file and remove duplicate value .

File output
# cat file
test
test
test1
test2

uniq command to file uniq value from file

# uniq file
test
test1
test2

Find out duplicate value from file

# uniq -d file
test

Note: as you seen from file test word is repeating twice or more than twice.

Find out duplicate value repeated count.

# uniq -D file
test
test