Make Claude's Shell Scripts Safer with set -euo pipefail

When Claude generates shell scripts for automation, CI steps, or deploy pipelines, ask it to include set -euo pipefail at the top of every script.

#!/bin/bash
set -euo pipefail

These three flags protect you from the most common shell scripting foot-guns:

• -e — exit immediately if any command fails (non-zero exit code)
• -u — treat unset variables as errors instead of silently expanding to empty
• -o pipefail — fail the whole pipeline if any command in it fails, not just the last one

Without these, a script like this silently swallows the failure:

# Without set -euo pipefail
get_user_ids | process_users | write_to_db
# If get_user_ids fails, the pipe still runs, writing nothing to the DB
# and the script exits 0 — success. You'll never know it broke.

With set -euo pipefail, the script halts on the failing step and exits non-zero — so CI fails loudly and nothing downstream runs on broken data.

You can add it to any script Claude generates in your prompt:

Write a bash deployment script. Use set -euo pipefail and add a
trap to clean up the temp directory on exit, even if something fails.

Claude will also add a trap clause for cleanup when you ask — so temp files, locks, and intermediate state get cleaned up even if the script crashes halfway through.

set -euo pipefail is the seatbelt for bash scripts — free, invisible when things work, essential when they don't.