Linux DevOps Practical Labs

Lab Set 1: Basic Skills

Lab 1.1: Wildcards and File Management

1. Create 10 files named test1.txt through test10.txt in a new directory called lab1
2. Create 5 files named report_jan.log, report_feb.log, report_mar.log, report_apr.log, report_may.log
3. List only files that start with “test” and have a single digit
4. List only files that end with .log extension
5. Copy all .txt files to a new directory called backup
6. Delete all files that start with “test” and end with numbers 6-9
7. Create files named data_A.csv, data_B.csv, data_C.csv
8. List only files that contain uppercase letters in their names
9. Rename all .log files to have a .backup extension instead
10. Find and list all .csv files in the current directory using the find command

Lab 1.2: Aliases and Productivity

1. Create a temporary alias called ll that shows detailed file listings with human-readable sizes
2. Create an alias called .. to go up one directory
3. List all currently active aliases in your session
4. Create an alias called ports to show all listening network ports
5. Remove the ll alias you created
6. Make your aliases permanent by adding them to the appropriate configuration file
7. Reload your configuration file to apply the changes without logging out

Lab 1.3: Environment Variables and PATH

1. Create a temporary environment variable called DB_HOST with value localhost
2. Create and export an environment variable called APP_ENV with value development
3. Display the value of your HOME environment variable
4. Display your current PATH variable in a readable format (one directory per line)
5. Create a directory called ~/mybin and add it to your PATH temporarily

Lab Set 2

Lab 2.1: File Permissions and Security

1. Create a file called secret.txt and set permissions so only you can read and write it (no access for group or others)

Lab 2.2: Number Systems and Permissions

1. Convert the permission rwxr-xr-x to its octal (numeric) representation
2. Convert the octal permission 644 to its symbolic representation
3. Convert the binary number 111101101 to octal format (for permissions)
4. If a file has permissions rw-r-----, calculate its numeric value
5. Convert the decimal number 255 to hexadecimal
6. Convert the hexadecimal number FF to binary
7. Convert the binary number 11111111 to decimal
8. Create a file with permissions rwxrwx--- using numeric notation
9. What would be the binary representation of the permission rwx------?
10. Calculate what permission chmod 777 represents in symbolic and binary format

Lab 2.3: Bashrc Configuration and Source

1. Open your .bashrc file and add a comment section for “Custom Aliases”
2. Add an alias for gs='git status' in your .bashrc
3. Add an alias for dc='docker-compose' in your .bashrc
4. Add a custom function called mkcd that creates a directory and changes into it in one command
5. Create a separate file called .bash_aliases for all your aliases
6. Modify your .bashrc to source (load) the .bash_aliases file if it exists
7. Create a file called .env with database connection variables
8. Source the .env file and verify the variables are loaded
9. Add a custom PS1 prompt configuration to your .bashrc
10. Reload your entire .bashrc without logging out to test all changes

Lab 2.4: Advanced Wildcards and Find

1. Create a complex directory structure: project/{src,tests,docs}/{js,py} with multiple files
2. Find all .js files in the entire project directory tree
3. Find all files that were modified in the last 24 hours
4. Find all files larger than 1MB in your home directory
5. Use wildcards to list only files that start with a vowel (a, e, i, o, u)
6. Find all executable files in /usr/bin that start with ‘git’
7. Delete all .tmp files recursively in your project directory (be careful!)
8. Find all empty files in the current directory and its subdirectories
9. Copy all .conf files from /etc that contain the word “network” in their name to a backup directory
10. Use character classes to find all files that start with a digit followed by exactly two letters

Lab Set 1 - Expected Outcomes

After completing Lab Set 1, you should be able to:

• ✅ Confidently use wildcards to match file patterns
• ✅ Create and manage aliases for common commands
• ✅ Work with environment variables and PATH
• ✅ Customize your bash prompt with colors and information
• ✅ Understand basic file operations and navigation

Lab Set 2 - Expected Outcomes

After completing Lab Set 2, you should be able to:

• ✅ Master file permissions in both numeric and symbolic formats
• ✅ Convert between different number systems (binary, octal, hexadecimal)
• ✅ Configure and customize your .bashrc effectively
• ✅ Use advanced find commands and wildcards
• ✅ Implement security best practices with file permissions

Hints and Tips

For Wildcards:

• Remember * matches zero or more characters
• Remember ? matches exactly one character
• Use [0-9] for digits, [a-z] for lowercase letters
• Character classes like [[:alpha:]] are very powerful

For Permissions:

• Read = 4, Write = 2, Execute = 1
• Add them together: rwx = 4+2+1 = 7
• Common patterns: 644 (files), 755 (executables), 700 (private)

For Environment Variables:

• Use export to make variables available to child processes
• Variables are case-sensitive
• Access with $VARIABLE_NAME or ${VARIABLE_NAME}

For .bashrc:

• Always test changes before making them permanent
• Keep backups of your configuration files
• Use source ~/.bashrc to reload without logging out
• Comment your customizations for future reference

Validation Commands

To verify your work:

# Check file permissions
ls -l filename

# Verify aliases
alias

# Check environment variables
printenv | grep VARIABLE_NAME

# View your prompt
echo $PS1

# Test command in PATH
which command_name

# Verify sourced variables
echo $VARIABLE_NAME

Additional Challenges (Optional)

Challenge 1: Create a Development Environment Setup Script

Write a script that:

• Sets up all necessary environment variables for a project
• Creates project directory structure
• Sets appropriate permissions on all directories
• Adds project bin directory to PATH
• Creates useful aliases for the project

Challenge 2: Permission Audit Script

Write a script that:

• Finds all world-writable files
• Finds all SUID/SGID files
• Checks for files with overly permissive settings
• Generates a security report

Challenge 3: Custom Bash Profile

Create a comprehensive .bashrc that includes:

• Organized sections with clear comments
• Useful aliases for your workflow
• Custom functions for common tasks
• A beautiful, informative prompt
• Smart PATH management
• Conditional configurations based on hostname or OS

Troubleshooting Guide

If aliases don’t work:

1. Check if you exported them (not needed for aliases, but needed for variables)
2. Ensure you sourced the file: source ~/.bashrc
3. Check for syntax errors in your alias definition

If PATH changes don’t work:

1. Make sure you used export
2. Verify the directory exists
3. Check for typos in the path
4. Ensure you reloaded your configuration

If permissions seem wrong:

1. Use ls -l to verify what was actually set
2. Remember: directories need x permission to be entered
3. Check both numeric and symbolic representations
4. Verify you have permission to change the file

If variables disappear:

1. Remember to export them
2. Add them to .bashrc for persistence
3. Check if you’re in the same shell session
4. Verify the syntax is correct