Shell Scripting taste

# Shell scripting taste of a DevOps engineer - Start every script with #!/usr/bin/env bash and set -euo pipefail. Confidence: 0.90 - Switch to Python or Go once a script passes about 100 lines or needs real data structures. Confidence: 0.85 - Run ShellCheck in CI and fix warnings instead of silencing them. Confidence: 0.95 - Format scripts with shfmt so diffs stay small. Confidence: 0.75 - Quote every variable expansion ("$var") unless word splitting is intended and commented. Confidence: 0.95 - Use [[ ]] for tests and $(...) for command substitution, never backticks. Confidence: 0.90 - Declare variables inside functions with local. Confidence: 0.85 - Put the logic in functions and call a main "$@" at the bottom of the file. Confidence: 0.80 - Clean up temporary files with mktemp and trap '...' EXIT. Confidence: 0.90 - Write errors and logs to stderr and keep stdout for data other tools can pipe. Confidence: 0.85 - Exit with a non-zero status and a clear message when something fails. Confidence: 0.90 - Provide a usage function and handle -h and --help. Confidence: 0.80 - Parse options with getopts or a simple case loop, not ad hoc positional checks. Confidence: 0.75 - Check required commands up front with command -v and fail early when one is missing. Confidence: 0.85 - Read configuration from environment variables with defaults, such as ${PORT:-8080}. Confidence: 0.80 - Never parse ls output; use globs or find -print0 with xargs -0. Confidence: 0.90 - Read files line by line with while IFS= read -r line. Confidence: 0.85 - Use arrays for argument lists instead of building command strings. Confidence: 0.85 - Avoid eval, and never pass untrusted input to it. Confidence: 0.95 - Make scripts idempotent so running them twice is safe. Confidence: 0.85 - Add a --dry-run flag to anything that deletes or changes remote state. Confidence: 0.80 - Stick to POSIX sh only when the script must run in minimal containers; otherwise target bash 4+. Confidence: 0.70