set -euo pipefail

Bash scripts are powerful, but they can fail silently, leaving subtle errors unnoticed and causing unexpected behavior. By enabling set -euo pipefail, you transform your script into a defensive, error-aware program. Each option serves a clear purpose: it stops execution on failures (-e), catches undefined variables (-u), ensures typos and misused variables are flagged, and makes pipelines fail if any command within them fails (-o pipefail).
Together, these four settings make your scripts safer, more predictable, and far less prone to hidden errors.

1. set -e

• Exits the script immediately if any command returns a non-zero status.
• Prevents continuing execution after a failed command.
• Example:

set -e
false   # Script stops here
echo "Won't run"

2. set -u

• Treats unset variables as errors.
• Helps catch typos and prevents using undefined values.
• Example:

set -u
echo $UNDEFINED_VAR  # Script exits here

3. set -o pipefail

• Ensures a pipeline fails if any command fails, not just the last one.
• Example:

set -o pipefail
false | true   # Script exits due to 'false'

4. Combining them

Using all three together is the standard for robust scripts:

#!/bin/bash
set -euo pipefail
echo "Safe script start"

set -euo pipefail is a cornerstone of safe Bash scripting. It provides early error detection, prevents silent failures, and ensures predictable behavior. Any production-ready or critical script should use it to avoid subtle bugs and data corruption.

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