Linux uniq command details how to use Linux uniq command

Uniq can check repeated columns in text files.

Syntax

Uniq [-cdu] [-f <column position>] [-s <character position>] [-w <character position>] [-- help] [-- version]

[Input file] [output file]

Parameters:

• -C or -- count displays the number of repeated occurrences of the row next to each column.
• -D or -- repeated only displays repeated columns.
• -F <field> or -- skip-fields = <field> ignores the specified field.
• -S <character location> or -- skip-chars = <character location> ignores the specified character.
• -U or -- unique only displays the row and column once.
• -W <character location> or -- check-chars = <character location> specifies the character to be compared.
• -- Help: displays help.
• -- Version: displays the version information.
• [Input file] specifies the sorted text file.
• [Output file] specifies the output file.

Instance

Use the uniq command to delete duplicate lines in the testfile of the 2nd, 5th, and 9th rows with the same behavior. You can use the following command:

Uniq testfile

The original content in testfile is:

$ Cat testfile # original content

Test 30

Test 30

Test 30

Hello 95

Hello 95

Hello 95

Hello 95

Linux 85

Linux 85

After you use the uniq command to delete duplicate rows, the following output is displayed:

$ Uniq testfile # delete the content of duplicate rows

Test 30

Hello 95

Linux 85

Check the file and delete repeated lines in the file, and display the number of repeated lines at the beginning of the row. Run the following command:

Uniq-c testfile

The output is as follows:

$ Uniq-ctestfile # delete the content of duplicate rows

3 test 30 # the preceding number indicates that the row appears three times in total.

4 Hello 95 # the preceding number indicates that this row appears four times.

2 Linux 85 # the preceding number indicates that this row appears twice.