sed (stream editor) basics in Linux CLI - Mini Project: Build & Apply

sed (stream editor) basics

📖 Scenario: You have a text file with a list of fruits and their quantities. You want to practice using sed to edit this file's content without opening a text editor.

🎯 Goal: Learn how to use sed commands to replace text, delete lines, and print specific lines from a file.

📋 What You'll Learn

Use sed commands to modify text

Replace specific words in the file

Delete a line containing a certain word

Print only a specific line from the file

💡 Why This Matters

🌍 Real World

Editing configuration files or logs quickly without opening an editor is common in system administration and automation.

💼 Career

Knowing sed helps automate text processing tasks, saving time and reducing errors in many IT and development roles.

1

Create the initial text file

Create a file named fruits.txt with these exact lines:
apple 10
banana 5
cherry 20
date 7
elderberry 3

Linux CLI

# Create the file fruits.txt with the given lines
# Your code here

Need a hint?

Use echo -e with newline characters \n and redirect output to fruits.txt.

2

Set the word to replace

Create a variable called old_word and set it to banana.
Create another variable called new_word and set it to blueberry.

Linux CLI

echo -e "apple 10\nbanana 5\ncherry 20\ndate 7\nelderberry 3" > fruits.txt
# Create variables old_word and new_word
# Your code here

Need a hint?

Use simple variable assignment like old_word=banana.

3

Replace the word using sed

Use sed with the s command to replace all occurrences of $old_word with $new_word in fruits.txt and save the output to a new file called fruits_updated.txt.

Linux CLI

echo -e "apple 10\nbanana 5\ncherry 20\ndate 7\nelderberry 3" > fruits.txt
old_word=banana
new_word=blueberry
# Use sed to replace old_word with new_word and save to fruits_updated.txt
# Your code here

Need a hint?

Use sed "s/$old_word/$new_word/g" fruits.txt > fruits_updated.txt to replace all occurrences.

4

Print the updated file content

Use cat to display the contents of fruits_updated.txt.

Linux CLI

echo -e "apple 10\nbanana 5\ncherry 20\ndate 7\nelderberry 3" > fruits.txt
old_word=banana
new_word=blueberry
sed "s/$old_word/$new_word/g" fruits.txt > fruits_updated.txt
# Display the contents of fruits_updated.txt
# Your code here

Need a hint?

Use cat fruits_updated.txt to see the updated file.