Appending to files (>>) in Bash Scripting

Introduction

Appending lets you add new information to the end of a file without erasing what is already there.

You want to keep a log of events happening in a script.

You need to add new lines to a configuration file without deleting existing settings.

You want to save multiple outputs from commands into one file over time.

You are collecting user inputs and want to store them one after another in a file.

Syntax

Bash Scripting

command >> filename

The double greater-than sign (>>) adds output to the file without removing existing content.

If the file does not exist, it will be created automatically.

Examples

Adds the word Hello to the end of greetings.txt.

Bash Scripting

echo "Hello" >> greetings.txt

Appends the current date and time to log.txt.

Bash Scripting

date >> log.txt

Adds the list of files in the current folder to files_list.txt.

Bash Scripting

ls >> files_list.txt

Sample Program

This script adds two lines to example.txt and then shows the file content.

Bash Scripting

#!/bin/bash

echo "First line" >> example.txt
echo "Second line" >> example.txt
cat example.txt

Important Notes

Using a single > will overwrite the file, deleting previous content.

Make sure you have write permission for the file or folder.

Appending is useful for logs because it keeps old data safe.

Summary

>> adds new content to the end of a file without deleting existing data.

If the file does not exist, it creates it automatically.

Use >> to keep adding information like logs or lists.