bash / set-e-exit-on-error

bash set -e — exit script on error

Quick Answer

#!/usr/bin/env bash
set -euo pipefail

# -e  exit on any non-zero exit code
# -u  treat unset variables as errors
# -o pipefail  pipelines fail on the first error, not just the last

Usage

Without set -e, bash scripts continue running after errors, which can cause silent data corruption or partial deploys.

Other causes & fixes

Allow a command to fail intentionally

set -e

# These patterns suppress the exit:
grep "pattern" file.txt || true
command_that_may_fail || echo "failed, continuing"

# Or temporarily disable
set +e
risky_command
set -e

set -u — catch undefined variables

set -u

echo "$UNDEFINED_VAR"
# bash: UNDEFINED_VAR: unbound variable → script exits

# Provide a default value to allow optional vars
echo "${OPTIONAL_VAR:-default}"

Trap errors for cleanup or logging

set -e

cleanup() {
  echo "Error on line $1" >&2
}
trap 'cleanup $LINENO' ERR

# Or always run cleanup on exit
trap 'cleanup' EXIT

set -e does not catch all failures

set -e is ignored in some contexts: if conditions, while/until tests, || and && lists.

# This will NOT exit even with set -e
if failing_command; then
  echo "success"
fi

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