How To Join Two Files In Linux

If you’re working in Linux and need to merge or join two files, you’re in luck. Linux provides a powerful and flexible command line tool called “join” that can do just that. This tutorial will guide you through the steps needed to join two files in Linux.

Understanding the “Join” Command

The join command in Linux is a text processing utility that combines lines from two files based on a common field. By default, it recognizes a space as the field separator and will merge lines with matching field values.

Basic Syntax

The basic syntax for the join command is as follows:


Joining Two Files

Here’s a step-by-step guide on how to join two files in Linux:

1. Create two files

For this tutorial, we’ll first create two simple text files. Here’s how to create a file and add some lines to it using the echo command:

        echo -e "1\n2\n3" > file1.txt
        echo -e "1\n2\n3" > file2.txt

2. Join the files

Now, we can join these two files. The basic command to join two files is:

        join file1.txt file2.txt

This will merge the lines from both files that have matching field values. The output will be:

1 1

2 2

3 3


The join command in Linux is a powerful tool for merging files based on a common field. It’s just one of the many utilities provided by the Linux command line that can make handling files and data more efficient. So the next time you need to merge two files in Linux, remember the join command!