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Linux Basics for Network Automation

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Linux is the foundation of most network automation tools. Understanding basic Linux commands and concepts is essential for anyone starting with network automation.

Why Linux for Network Automation?

  • Most automation tools run on Linux
  • Command-line efficiency for automation workflows
  • Better integration with development tools
  • Cost-effective and open-source

Essential Commands for Network Automation

File and Directory Management

# Navigate directories
cd /path/to/directory    # Change directory
pwd                      # Print working directory
ls -la                   # List files with details

# Create and manage files
mkdir automation         # Create directory
touch playbook.yml       # Create empty file
cp source dest           # Copy files
mv old_name new_name     # Move/rename files
rm filename              # Remove file
rm -rf directory         # Remove directory recursively

File Editing

# Text editors (choose one)
nano playbook.yml        # Simple editor for beginners
vim playbook.yml         # Advanced editor
code playbook.yml        # Visual Studio Code (if installed)

File Permissions

# View permissions
ls -la

# Change permissions
chmod +x script.sh       # Make executable
chmod 600 private_key    # Secure private key
chown user:group file    # Change ownership

Package Management

# Ubuntu/Debian
sudo apt update
sudo apt install package_name

# CentOS/RHEL
sudo yum install package_name
# or
sudo dnf install package_name

# Python packages
pip install ansible
pip install --user ansible  # Install for current user only

Process Management

# View running processes
ps aux | grep ansible
top                        # Interactive process viewer
htop                       # Enhanced top (if installed)

# Kill processes
kill process_id
killall process_name

Network Commands

# Network connectivity
ping 192.168.1.1
ssh user@hostname
scp file user@hostname:/path/
wget https://example.com/file
curl https://api.example.com/data

# Network information
ip addr show
ip route show
netstat -tuln
ss -tuln

Environment and Variables

# View environment variables
env
echo $PATH
echo $HOME

# Set variables
export ANSIBLE_HOST_KEY_CHECKING=False
export EDITOR=nano

# Persistent variables (add to ~/.bashrc)
echo 'export ANSIBLE_HOST_KEY_CHECKING=False' >> ~/.bashrc
source ~/.bashrc

Working with Text Files

Viewing Files

# View entire file
cat filename

# View file page by page
less filename
more filename

# View beginning/end of file
head -20 filename
tail -20 filename
tail -f logfile    # Follow log file in real-time

Searching in Files

# Search for text in files
grep "search_term" filename
grep -r "search_term" directory/    # Recursive search
grep -i "search_term" filename      # Case insensitive

# Find files
find . -name "*.yml"               # Find YAML files
find . -type f -name "*.py"        # Find Python files

Shell Scripting Basics

Simple Script Example

#!/bin/bash
# This is a comment

# Variables
HOSTNAME="192.168.1.1"
USERNAME="admin"

# Commands
echo "Connecting to $HOSTNAME..."
ssh $USERNAME@$HOSTNAME "show version"

Make Script Executable

chmod +x script.sh
./script.sh

Virtual Environments

Python Virtual Environment

# Create virtual environment
python3 -m venv automation_env

# Activate virtual environment
source automation_env/bin/activate    # Linux/macOS
# automation_env\Scripts\activate     # Windows

# Deactivate
deactivate

# Install packages in virtual environment
pip install ansible
pip install -r requirements.txt

File System Navigation

Common Directories

/home/username/          # User home directory
/etc/                    # System configuration
/var/log/               # Log files
/tmp/                   # Temporary files
/usr/local/bin/         # User-installed programs

Path Management

# Add directory to PATH
export PATH=$PATH:/path/to/scripts

# Check if command exists
which ansible
whereis ansible

Best Practices

  1. Use Tab Completion: Press Tab to auto-complete commands and filenames
  2. Use History: Press Up/Down arrows to navigate command history
  3. Use Aliases: Create shortcuts for common commands
  4. Backup Important Files: Always backup before making changes
  5. Use Absolute Paths: When in doubt, use full paths

Common Aliases for Network Automation

Add these to your ~/.bashrc:

# Network automation aliases
alias ansible-playbook='ansible-playbook -i inventory'
alias ansible-inventory='ansible-inventory --list -i inventory'
alias ansible-doc='ansible-doc -t module'

# Quick navigation
alias ll='ls -la'
alias ..='cd ..'
alias ...='cd ../..'

Learn More

Next Steps

Once you're comfortable with Linux basics, explore: - Ansible Introduction & Getting Started - Visual Studio Code for Network Automation - Git Basics for Version Control