Backticks and $() for command substitution in Bash Scripting - Mini Project: Build & Apply

Using Backticks and $() for Command Substitution in Bash

📖 Scenario: You are writing a simple bash script to display information about files in a directory. You want to capture the output of commands and use it inside your script.

🎯 Goal: Learn how to use backticks `command` and $(command) to run commands inside your script and store their output in variables.

📋 What You'll Learn

Create a variable with the output of a command using backticks

Create a variable with the output of a command using $() syntax

Use these variables in your script

Print the results to the terminal

💡 Why This Matters

🌍 Real World

Command substitution is used in scripts to capture the output of commands and use it for decisions, calculations, or messages.

💼 Career

Knowing how to capture command output is essential for writing effective bash scripts in system administration, automation, and DevOps roles.

1

Create a variable using backticks for command substitution

Create a variable called file_count_backticks that stores the number of files in the current directory using the command ls | wc -l inside backticks.

Bash Scripting

# Create a variable called file_count_backticks using backticks
# Your code here

Need a hint?

Use backticks ` around the command ls | wc -l to capture its output.

2

Create a variable using $() for command substitution

Create a variable called file_count_dollar that stores the number of files in the current directory using the command ls | wc -l inside $( ).

Bash Scripting

file_count_backticks=`ls | wc -l`
# Create a variable called file_count_dollar using $( )
# Your code here

Need a hint?

Use $(command) syntax to capture the output of ls | wc -l.

3

Use the variables in a message

Write a line that creates a variable called message with the text: "There are X files (backticks) and Y files ($()) in the directory." where X is the value of file_count_backticks and Y is the value of file_count_dollar. Use double quotes and variable substitution.

Bash Scripting

file_count_backticks=`ls | wc -l`
file_count_dollar=$(ls | wc -l)
# Create a variable message with the counts inside a sentence
# Your code here

Need a hint?

Use double quotes and $variable to insert variable values inside the string.

4

Print the message to the terminal

Write a line to print the variable message to the terminal using echo.

Bash Scripting

file_count_backticks=`ls | wc -l`
file_count_dollar=$(ls | wc -l)
message="There are $file_count_backticks files (backticks) and $file_count_dollar files ($()) in the directory."
# Print the message variable
# Your code here

Need a hint?

Use echo "$message" to print the message with variable values.