⚠️ OWASP, Bash & DevOps

# Create files
touch file.txt                    # Create empty file
echo "Hello" > file.txt           # Create with content
cat > file.txt                    # Create and type (Ctrl+D to save)

# View file contents
cat file.txt                      # Display entire file
less file.txt                     # View with paging
head -n 20 file.txt              # First 20 lines
tail -f /var/log/syslog          # Follow log in real-time

# Copy files
cp source.txt dest.txt            # Copy file
cp -r /source/dir /dest/dir       # Copy directory recursively

# Move/Rename
mv old.txt new.txt                # Rename
mv file.txt /new/location/        # Move

# Delete
rm file.txt                       # Delete file
rm -rf directory/                 # Delete directory (dangerous!)

# Permissions
chmod 755 script.sh               # rwxr-xr-x
chmod +x script.sh                # Add execute
chown user:group file.txt         # Change owner

# Navigate
pwd                               # Print working directory
cd /path/to/directory             # Change directory
cd ~                              # Go to home directory
cd -                              # Go to previous directory
cd ..                             # Go up one level
cd ../..                          # Go up two levels

# List contents
ls                                # List files
ls -l                             # Long format
ls -la                            # Include hidden files
ls -lh                            # Human-readable sizes
ls -lt                            # Sort by time

# Create/Remove directories
mkdir new_directory               # Create directory
mkdir -p path/to/nested/dir       # Create nested
rmdir empty_directory             # Remove empty
rm -r directory/                  # Remove with contents

# Set environment variables (temporary)
export API_KEY="your-key-here"
export DB_HOST="localhost"
export FLASK_ENV="development"

# View variables
echo $API_KEY                     # Display specific variable
echo $HOME                        # Home directory
echo $PATH                        # Executable search path
env                               # List all variables
printenv                          # Same as env

# Unset variable
unset API_KEY

# Set permanently (add to ~/.bashrc)
echo 'export API_KEY="your-key"' >> ~/.bashrc
source ~/.bashrc                  # Reload configuration

# Common environment variables
$HOME                             # User home directory
$USER                             # Current username
$PATH                             # Executable search paths
$PWD                              # Present working directory
$SHELL                            # Current shell

# GitLab CI/CD Example
stages:
  - build
  - test
  - deploy

build:
  stage: build
  script:
    - pip install -r requirements.txt
    - python setup.py build

test:
  stage: test
  script:
    - pytest tests/
    - coverage report

deploy:
  stage: deploy
  script:
    - docker build -t myapp .
    - docker push myapp

# Terraform Example
resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"
  
  tags = {
    Name = "WebServer"
    Environment = "Production"
  }
}