shell-best-practices

Bash scripts fail on unquoted variables, unset parameters, and uncaught errors. Use strict mode—add `set -euo pipefail` after the shebang—to exit on errors, treat unset variables as fatal, and catch pipeline failures. Quote all variables and validate inputs before use.

Error handling in shell scripts requires three layers: strict mode flags (`set -euo pipefail`), explicit error checks after each command, and trap handlers to clean up on exit. Combine these with meaningful error messages so failures are debuggable across environments.

Portable shell scripts use a POSIX-compatible shebang, avoid bash-only syntax, apply consistent quoting and variable naming, and validate inputs at runtime. Use `set -euo pipefail` and test across target environments to catch environment-specific breakage early.

Shell scripts are vulnerable to command injection through unquoted variables, unsafe input parsing, and inadequate parameter validation. Enforce input validation, quote all expansions, use arrays instead of string splitting, and apply strict mode to catch uninitialized variables before they execute.

Yes. The shebang—the first line starting with `#!`—tells the system which interpreter to use. For portable bash scripts, use `#!/bin/bash` or `#!/usr/bin/env bash`. Follow the shebang immediately with `set -euo pipefail` to enforce strict error handling.

Unsafe loops and arrays cause word-splitting and globbing bugs. Use proper array syntax with quoted expansions like `"${array[@]}"`, iterate with `for item in "${array[@]}"; do`, and avoid bare variable expansion in loops to maintain robust, maintainable scripts.