Retention that never ran

$retention_cleanup.sh --path /var/log/app --days 30

#!/usr/bin/env bash
$set -euo pipefail
$IFS=$'\n\t'
 
# retention_cleanup.sh - plan and apply age-based file retention.
#
# Fixes: a retention rule that lives in a wiki and never ran, so the volume
# fills one old log at a time until a write fails at 03:00.
#
# The default is a dry run: it prints every file it would delete, the oldest
# first, and the total reclaimable. Nothing is removed until --apply.
#
# Usage:
#   retention_cleanup.sh --path /var/log/app --days 30
#   retention_cleanup.sh --path /var/log/app --days 30 --apply
#   retention_cleanup.sh --path /var/log/app --days 30 --pattern '*.log'
#
# Cron (report every Monday at 06:00, apply every night at 03:15):
#   0 6 * * 1 /usr/local/bin/retention_cleanup.sh --path /var/log/app \
#     --days 30 >> /var/log/retention.log 2>&1
#   15 3 * * * /usr/local/bin/retention_cleanup.sh --path /var/log/app \
#     --days 30 --apply >> /var/log/retention.log 2>&1
#
# Exit codes:
#   0  nothing matched (dry run) or every planned file was deleted (apply)
#   1  files matched (dry run) or at least one deletion failed (apply)
#   2  usage error, unreadable path, or a failed scan
#
# Requires GNU find (find -printf), GNU sort (sort -z) and numfmt
# (coreutils). Tested on a fixture tree in /tmp: clean exit 0, dirty exit 1,
# missing args exit 2.
# By s0sta.com
 
$PROG=${0##*/}
$path=""
$days=30
$pattern="*"
$max_delete=10000
$apply=0
$tmp=""
 
$usage() {
$  cat <<'EOF'
retention_cleanup.sh - plan and apply age-based file retention
 
Usage:
  retention_cleanup.sh --path DIR --days N [options]
 
Options:
  --path DIR        directory to scan (required, not / and not a symlink)
  --days N          age in whole days; default 30
  --pattern GLOB    only files whose name matches GLOB; default '*'
  --max-delete N    refuse to apply more than N deletions; default 10000
  --apply           delete the files; without it nothing is removed
  -h, --help        show this help and exit 0
 
Examples:
  retention_cleanup.sh --path /var/log/app --days 30
  retention_cleanup.sh --path /var/log/app --days 30 --pattern '*.log'
  retention_cleanup.sh --path /var/log/app --days 30 --apply
 
Exit: 0 nothing to do, 1 files matched or a deletion failed, 2 usage.
EOF
$}
 
$die() {
$  printf '%s: %s\n' "$PROG" "$1" >&2
$  exit 2
$}
 
# shellcheck disable=SC2329  # called by the EXIT trap
$cleanup() {
$  if [[ -n $tmp ]]; then
$    rm -f -- "$tmp"
$  fi
$}
$trap cleanup EXIT
 
$fmt_bytes() {
$  if (($1 == 0)); then
$    printf '0B'
$    return
$  fi
$  numfmt --to=iec --suffix=B --format='%.1f' -- "$1"
$}
 
$while (($#)); do
$  case $1 in
$    --path)
$      [[ $# -ge 2 ]] || die "--path needs a directory"
$      path=$2
$      shift 2
$      ;;
$    --days)
$      [[ $# -ge 2 ]] || die "--days needs a number"
$      days=$2
$      shift 2
$      ;;
$    --pattern)
$      [[ $# -ge 2 ]] || die "--pattern needs a glob"
$      pattern=$2
$      shift 2
$      ;;
$    --max-delete)
$      [[ $# -ge 2 ]] || die "--max-delete needs a number"
$      max_delete=$2
$      shift 2
$      ;;
$    --apply)
$      apply=1
$      shift
$      ;;
$    -h|--help)
$      usage
$      exit 0
$      ;;
$    --)
$      shift
$      break
$      ;;
$    -*)
$      die "unknown option: $1 (try --help)"
$      ;;
$    *)
$      die "unexpected argument: $1 (try --help)"
$      ;;
$  esac
$done
 
$[[ -n $path ]] || die "--path is required (try --help)"
$[[ $days =~ ^[0-9]+$ ]] || die "--days must be a whole number"
$((days >= 1)) || die "--days must be at least 1"
$[[ $max_delete =~ ^[0-9]+$ ]] || die "--max-delete must be a whole number"
$((max_delete >= 1)) || die "--max-delete must be at least 1"
$[[ -d $path ]] || die "not a directory: $path"
$if [[ -L $path ]]; then
$  die "refusing a symlink path: $path"
$fi
$while [[ $path == */ && $path != "/" ]]; do
$  path=${path%/}
$done
$[[ -n $path ]] || die "refusing to scan /"
$[[ -r $path ]] || die "cannot read: $path"
$command -v find >/dev/null 2>&1 || die "find is not installed"
$command -v sort >/dev/null 2>&1 || die "sort is not installed"
$command -v numfmt >/dev/null 2>&1 || die "numfmt is not installed (coreutils)"
 
$tmp=$(mktemp "${TMPDIR:-/tmp}/retention.XXXXXX") || die "mktemp failed"
$if ! find "$path" -xdev -type f -mtime +"$days" -name "$pattern" \
      -printf '%T@ %s %p\0' | sort -z -n >"$tmp"; then
$  die "scan failed under: $path"
$fi
 
$now=$(date +%s)
$total=0
$count=0
$while IFS= read -r -d '' rec; do
$  rest=${rec#* }
$  size=${rest%% *}
$  count=$((count + 1))
$  total=$((total + size))
$done <"$tmp"
 
$printf 'MODE %s\n' "$([[ $apply -eq 1 ]] && printf apply || printf dry-run)"
$printf 'PATH %s\n' "$path"
$printf 'OLDER %d days\n' "$days"
$printf 'MATCH %d files, %s reclaimable\n' "$count" "$(fmt_bytes "$total")"
 
$if ((count == 0)); then
$  printf 'OK nothing older than %d days under %s\n' "$days" "$path"
$  exit 0
$fi
 
$shown=0
$while IFS= read -r -d '' rec; do
$  if ((shown >= 10)); then
$    break
$  fi
$  stamp=${rec%% *}
$  rest=${rec#* }
$  size=${rest%% *}
$  file=${rest#* }
$  age=$(((now - ${stamp%%.*}) / 86400))
$  rel=${file#"$path"/}
$  printf 'RM %s %dd %s\n' "$rel" "$age" "$(fmt_bytes "$size")"
$  shown=$((shown + 1))
$done <"$tmp"
 
$if ((count > shown)); then
$  printf 'MORE %d files not listed\n' "$((count - shown))"
$fi
 
$if ((apply == 0)); then
$  printf 'DRY-RUN nothing deleted. Add --apply to delete.\n'
$  exit 1
$fi
 
$if ((count > max_delete)); then
$  printf 'REFUSE %d files exceeds --max-delete %d; nothing deleted\n' \
    "$count" "$max_delete"
$  exit 1
$fi
 
$removed=0
$failed=0
$freed=0
$while IFS= read -r -d '' rec; do
$  rest=${rec#* }
$  size=${rest%% *}
$  file=${rest#* }
$  if rm -f -- "$file"; then
$    removed=$((removed + 1))
$    freed=$((freed + size))
$  else
$    failed=$((failed + 1))
$    printf 'FAIL could not delete %s\n' "$file" >&2
$  fi
$done <"$tmp"
 
$printf 'DELETED %d files, %s freed\n' "$removed" "$(fmt_bytes "$freed")"
$if ((failed > 0)); then
$  printf 'FAIL %d deletions failed\n' "$failed"
$  exit 1
$fi
$exit 0