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Hello World!

Learning objectives

  1. Utilize simple bash commands to manipulate strings

A Hello, World! is a minimalist example that is meant to demonstrate the basic syntax and structure of a programming language or software framework. The example typically consists of printing the phrase 'Hello World!' to the output, such as the console or terminal, or writing it to a file.

Let's demonstrate this with simple commands that you can run directly in the terminal.

The echo command in Linux is a built-in command that allows users to display lines of text or strings that are passed as arguments. It is commonly used in shell scripts and batch files to output status text to the screen or a file.

The most straightforward usage of the echo command is to display a text or string on the terminal. To do this, you simply provide the desired text or string as an argument to the echo command:

echo <string>

Exercise

Use the echo command to print the string 'Hello World!' to the terminal.

Solution 
echo 'Hello World!'

Redirect outputs

The output of the echo can be redirected to a file instead of displaying it on the terminal. You can achieve this by using the > operator for output redirection. For example:

echo 'Welcome!' > output.txt

This will write the output of the echo command to the file name output.txt.

Exercise

Use the > operator to redirect the output of echo to a file named output.txt.

Solution 
echo 'Hello World!' > output.txt

List files

The Linux shell command ls lists directory contents of files and directories. It provides valuable information about files, directories, and their attributes.

ls will display the contents of the current directory:

ls

Exercise

List the files in the working directory to verify output.txt was created.

Solution 
ls

A file named output.txt should now be listed in your current directory.

View file contents

The cat command in Linux is a versatile companion for various file-related operations, allowing users to view, concatenate, create, copy, merge, and manipulate file contents.

The most basic use of cat is to display the contents of a file on the terminal. This can be achieved by simply providing the filename as an argument:

cat <file name>

Exercise

Use the cat command to print the contents of output.txt.

Solution 
cat output.txt

You should see Hello World! printed to your terminal.

Summary

In this step you have learned:

  1. How to use the echo command to print a string to the terminal
  2. How to use the > operator to redirect the output of echo
  3. How to use the ls command to list the files in your working directory
  4. How to use the cat command to print the contents of files