directories

#!/bin/bash

# SYNNOPSIS
# ----------------
# leave_n_files N PATTERN
# leave_n_dirs  N PATTERN
#   return PATTERN matched files/directories but the latest(mtime) N files/directories.

# EXAMPLE
# ----------------
# for i in $(leave_n_dirs 7 '/var/backup/db/2???????'); do # y3k problem
#   echo rm -fr "$i"
# done
#
# leave_n_files 3 '/var/backup/db/*.dmp' | ( IFS=''; \
#   while read -r i; do
#     echo rm -f "$i"
#   done)

_leave_n_objs() {
  n=$1
  pat="$2"
  type=$3

  [ $# = 3 ] || { echo "missing args" 1>&2; return 1; }

  target_dir=${pat%/*}
  filename_pat=${pat##*/}

  find "$target_dir" -maxdepth 1 -name "$filename_pat" -a -type "$type" -print0 | \
    xargs -r0 ls -trd | \
    head -n -${n}
}

leave_n_files() { _leave_n_objs "$@" 'f'; }
leave_n_dirs()  { _leave_n_objs "$@" 'd'; }