Scripting Basics

Why Learn Shell & Python Scripting?

• Efficiency: Automate repetitive command-line tasks in seconds.
• Reproducibility: Ensure the same steps run identically every time.
• Portability: Scripts work across environments (Linux, macOS, WSL).

Bash Scripting Fundamentals

Shebang & Execution Permissions

#!/usr/bin/env bash

• Place at the top of your script to select the interpreter.
• Make executable: chmod +x script.sh.

Variables & Parameter Expansion

NAME="MyApp"
echo "Deploying $NAME version ${VERSION:-latest}"

• Use ${VAR:-default} for safe defaults.
• Quote variables ("$VAR") to prevent word-splitting.

Control Structures

if [[ -f "/etc/config.yml" ]]; then
  echo "Config exists"
else
  echo "Missing config"
  exit 1
fi

for file in *.log; do
  gzip "$file"
done

• if/then/else, for, while, case blocks provide flow control.