A detailed description of the Uniq command under Linux

-C adds the number of times each line appears in the input file before the output line.

-D displays only duplicate rows.

-U displays only rows that are not duplicates.

Example

1, go to heavy, there are many lines of the same display only one line
Cat 4.txt |sort-n | Uniq-c
2, the output line repeats the number of times, the number of repetitions from large to small sequence output
Cat 4.txt |sort-n | Uniq-d
3. Output a unique line, that is, no duplicate rows
Cat 4.txt |sort-n | Uniq-u

A detailed description of the Uniq command under Linux