set -euo pipefail & trap in Bash

From the Bash Scripting cheat sheet · Exit Codes & Error Handling · verified Jul 2026

Strict mode and cleanup handlers.

bash

# Quick Reference
set -euo pipefail       # strict mode (put near the top)
trap 'echo "cleanup"' EXIT
trap 'echo "error on line $LINENO"' ERR

💡 Start scripts with set -euo pipefail so failures stop the script instead of cascading.

⚡ trap ... EXIT guarantees cleanup (temp files, locks) runs on every exit path.

📌 With -u, reference optional vars as ${VAR:-} to avoid an unbound-variable error.

🟢 Send error messages to stderr with >&2 so they are not captured by $(...).

error-handlingsettrap