Bash Error Handling Shell Script

Scripts that fail halfway through a backup or migration are worse than scripts that fail loudly at the start. This pattern combines set -euo pipefail with trap handlers so every run logs start time, failing line, and exit code — ideal for cron mail and monitoring.

What this script does

Enables set -euo pipefail for strict failure semantics
Logs the failing command and line number on ERR
Always logs script end and exit code on EXIT
Wraps any command or script path passed as an argument
Returns the wrapped command’s exit code for cron alerting

Prerequisites

Bash 4+ on Linux
Write access to /var/log or your log directory
Scripts you wrap must be executable

Step 1: Save the script

sudo nano /usr/local/bin/safe-run.sh
sudo chmod +x /usr/local/bin/safe-run.sh

Step 2: Full script (scroll to read)

safe-run.sh

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

LOG="/var/log/safe-run.log"
TARGET="${1:?usage: safe-run.sh /path/to/script [args...]}"
shift || true

log(){ echo "[$(date '+%F %T')] $*" | tee -a "$LOG"; }

on_err(){
  local ec=$?
  log "ERROR: command failed (exit $ec) at ${BASH_SOURCE[1]}:${BASH_LINENO[0]}: ${BASH_COMMAND}"
  return "$ec"
}

on_exit(){
  local ec=$?
  log "END ${TARGET##*/} exit=$ec"
  exit "$ec"
}

trap on_err ERR
trap on_exit EXIT

log "START ${TARGET##*/} $*"
exec "$TARGET" "$@"

Scroll inside the box to read the full script.

Step 3: Configure settings

LOG — append-only log file for all wrapped runs
Pass the target script as the first argument; remaining args are forwarded
Pair with email from cron: MAILTO= or your monitoring stack
See also our shell scripting guide for basics

Bash trap error handling shell script logging a failed command

Step 4: Test manually

sudo install -m 755 safe-run.sh /usr/local/bin/safe-run.sh

sudo safe-run.sh /bin/false; echo exit=$?

sudo tail -5 /var/log/safe-run.log

Schedule with cron

sudo crontab -e

Add:

0 2 * * * /usr/local/bin/safe-run.sh /usr/local/bin/mysql-backup.sh

Bash Error Handling Shell Script: trap, set -euo pipefail and Safe Wrappers