File descriptors and redirection in Bash Scripting - Mini Project: Build & Apply

File Descriptors and Redirection in Bash

📖 Scenario: You are working on a small bash script to manage output messages. You want to separate normal messages from error messages by using file descriptors and redirection.

🎯 Goal: Build a bash script that writes a normal message to standard output and an error message to standard error using file descriptors and redirection.

📋 What You'll Learn

Create a file descriptor for error messages

Redirect error messages to a separate file

Write a normal message to standard output

Write an error message to the error file using the file descriptor

Display the contents of both output and error files

💡 Why This Matters

🌍 Real World

Separating normal output and error messages helps in debugging scripts and logging important information separately.

💼 Career

Understanding file descriptors and redirection is essential for writing robust shell scripts used in system administration and automation tasks.

1

Create output and error files

Create two empty files called output.txt and error.txt using the touch command.

Bash Scripting

# Create the files output.txt and error.txt
# Your code here

Need a hint?

Use the touch command to create empty files.

2

Redirect file descriptor 3 to error.txt

Add a command to redirect file descriptor 3 to write to the file error.txt.

Bash Scripting

touch output.txt error.txt
# Redirect file descriptor 3 to error.txt
# Your code here

Need a hint?

Use exec 3>error.txt to open file descriptor 3 for writing to error.txt.

3

Write messages using redirection

Write the message "This is a normal message." to output.txt using standard output redirection, and write the message "This is an error message." to error.txt using file descriptor 3.

Bash Scripting

touch output.txt error.txt
exec 3>error.txt
# Write normal message to output.txt
# Write error message to error.txt using fd 3
# Your code here

Need a hint?

Use echo "message" > output.txt for normal output and echo "message" >&3 to write to file descriptor 3.

4

Display contents of output and error files

Print the contents of output.txt and error.txt using the cat command to show the messages stored in each file.

Bash Scripting

touch output.txt error.txt
exec 3>error.txt
 echo "This is a normal message." > output.txt
 echo "This is an error message." >&3
# Print contents of output.txt and error.txt
# Your code here

Need a hint?

Use cat output.txt and cat error.txt to display the contents of the files.