Your question: How do I print duplicate lines in Linux?

To make uniq print only duplicate lines, use the -D command line option. For example, suppose file1 now contains an extra line at the bottom (note that this line is not repeated). As you can see, the -D option makes uniq display all repeated lines in output, including all their repetitions.

How do you find duplicate lines in Unix?

The uniq command in UNIX is a command line utility for reporting or filtering repeated lines in a file. It can remove duplicates, show a count of occurrences, show only repeated lines, ignore certain characters and compare on specific fields.

What does uniq do 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.

How do you copy a line in Linux?

The uniq command is used to remove duplicate lines from a text file in Linux. By default, this command discards all but the first of adjacent repeated lines, so that no output lines are repeated. Optionally, it can instead only print duplicate lines. For uniq to work, you must first sort the output.

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How use uniq command in Linux?

Methods to Use Uniq Command in Linux with Examples

  1. 1) Omit duplicates. …
  2. 2) Display number of repeated lines. …
  3. 3) Print only the duplicates. …
  4. 4) Ignore case when comparing. …
  5. 5) Only print unique lines. …
  6. 6) Sort and find duplicates. …
  7. 7) Save the output in another file. …
  8. 8) Ignore characters.

How do I remove duplicate lines in Unix?

You need to use shell pipes along with the following two Linux command line utilities to sort and remove duplicate text lines:

  1. sort command – Sort lines of text files in Linux and Unix-like systems.
  2. uniq command – Rport or omit repeated lines on Linux or Unix.

How do I find duplicate lines in two files?

Each file contains a line with a string sentence; they are sorted and duplicate lines removed with sort file1 | uniq . And the output should output the lines that appears in both files.

How do you grep unique lines in Linux?


  1. Using grep and head command. Pipe the output of grep command to head command to get the first line. …
  2. Using m option of grep command. The m option can be used to display the number of matching lines. …
  3. Using the sed command. We can also use the sed command to print unique occurrence of a pattern. …
  4. Using awk command.

What is the use of awk in Linux?

Awk is a utility that enables a programmer to write tiny but effective programs in the form of statements that define text patterns that are to be searched for in each line of a document and the action that is to be taken when a match is found within a line. Awk is mostly used for pattern scanning and processing.

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What is the use of in Linux?

The ‘!’ symbol or operator in Linux can be used as Logical Negation operator as well as to fetch commands from history with tweaks or to run previously run command with modification. All the commands below have been checked explicitly in bash Shell.

How do you find repeated words in Linux?


  1. First you can tokenize the words with grep -wo , each word is printed on a singular line.
  2. Then you can sort the tokenized words with sort .
  3. Finally can find consecutive unique or duplicate words with uniq . 3.1. uniq -c This prints the words and their count.

How many types of permissions a file has in Unix?

Explanation: In UNIX system, a file can have three types of permissions -read, write and execute. Read permission means that the file is readable.

How do I grep a file in Linux?

How to use the grep command in Linux

  1. Grep Command Syntax: grep [options] PATTERN [FILE…] …
  2. Examples of using ‘grep’
  3. grep foo /file/name. …
  4. grep -i “foo” /file/name. …
  5. grep ‘error 123’ /file/name. …
  6. grep -r “” /etc/ …
  7. grep -w “foo” /file/name. …
  8. egrep -w ‘word1|word2’ /file/name.
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