Install Duplo Duplicate Code Finder on Ubuntu 26.04

Duplo is a command-line utility for detecting the duplicated sections of source code. It can scan files, identify repeated blocks, and report the locations and number of duplicate lines. Duplo supports C, C++, C#, Java, and other programming languages. This tutorial shows how to install Duplo duplicate code finder on Ubuntu 26.04.

Prepare environment

Duplo release is distributed as a ZIP archive, so the unzip package is required before installation.

sudo apt update

sudo apt install -y unzip

Install Duplo

Download the latest archive from the GitHub releases page:

curl -sSLo duplo.zip https://github.com/dlidstrom/Duplo/releases/latest/download/duplo-linux.zip

Extract the Duplo executable into /usr/local/bin:

sudo unzip -q duplo.zip duplo -d /usr/local/bin

The downloaded archive is no longer needed after extraction and can be removed:

rm -rf duplo.zip

Testing Duplo

A small C source file containing two identical functions provides a straightforward test. Create a test.c file:

nano test.c

Add the following content:

#include <stdio.h>

void process_user(const char *name, const int age, const char *email) {
    printf("Processing user...\n");
    printf("User: %s\n", name);
    printf("Age: %d\n", age);
    printf("User: %s\n", email);
}

void process_customer(const char *name, const int age, const char *email) {
    printf("Processing user...\n");
    printf("User: %s\n", name);
    printf("Age: %d\n", age);
    printf("User: %s\n", email);
}

Duplo accepts two positional arguments: the first specifies where the list of files comes from, while the second specifies where the analysis results are written. A hyphen (-) represents standard input or standard output, depending on its position. Run Duplo with the filename supplied through standard input and writing results to standard output:

echo 'test.c' | duplo - -

The output should look the following:

Loading and hashing files ... 1 done.

test.c(11)
test.c(4)
    printf("Processing user...\n");
    printf("User: %s\n", name);
    printf("Age: %d\n", age);
    printf("User: %s\n", email);

test.c found: 1 block(s)
Configuration:
  Number of files: 1
  Minimal block size: 4
  Minimal characters in line: 3
  Ignore preprocessor directives: 0
  Ignore same filenames: 0

Results:
  Lines of code: 11
  Duplicate lines of code: 4
  Total 1 duplicate block(s) found.

The report indicates that Duplo found one duplicated block. Four lines of code are identified as duplicates, confirming that the duplicate-code scanner is operating correctly.

Uninstall Duplo

When Duplo is no longer required, remove its executable:

sudo rm -rf /usr/local/bin/duplo