Bash scripting – pattern an toàn hay dùng

#!/usr/bin/env bash
set -euo pipefail
 
usage() {
  echo "Usage: $0 [-n] [-o outdir] -f hosts.txt" >&2
  exit 2
}
 
log() { printf '%s %s\n' "$(date -Is)" "$*" >&2; }
 
DRY_RUN=0
OUTDIR="./out"
HOSTS_FILE=""
 
while getopts ":nf:o:h" opt; do
  case "$opt" in
    n) DRY_RUN=1 ;;
    f) HOSTS_FILE="$OPTARG" ;;
    o) OUTDIR="$OPTARG" ;;
    h) usage ;;
    :) echo "Thiếu giá trị cho -$OPTARG" >&2; usage ;;
    \?) echo "Option không hợp lệ: -$OPTARG" >&2; usage ;;
  esac
done
shift $((OPTIND - 1))
[[ -n "$HOSTS_FILE" ]] || usage
 
TMPDIR_RUN="$(mktemp -d)"
cleanup() { rm -rf -- "$TMPDIR_RUN"; }
trap cleanup EXIT
trap 'log "Lỗi tại dòng $LINENO: $BASH_COMMAND"' ERR
 
mkdir -p "$OUTDIR"
failed=()
while IFS= read -r host; do
  [[ -z "$host" || "$host" == \#* ]] && continue
  log "Backup $host"
  if (( DRY_RUN )); then continue; fi
  if ssh -n -o BatchMode=yes -o ConnectTimeout=10 "$host" 'show running-config' \
      > "$TMPDIR_RUN/$host.cfg"; then
    mv "$TMPDIR_RUN/$host.cfg" "$OUTDIR/$host-$(date +%F).cfg"
  else
    failed+=("$host")
  fi
done < "$HOSTS_FILE"
 
if (( ${#failed[@]} )); then
  log "Thất bại: ${failed[*]}"
  exit 1
fi