File: last.sh
   1 #!/bin/sh
   2 
   3 # The MIT License (MIT)
   4 #
   5 # Copyright (c) 2026 pacman64
   6 #
   7 # Permission is hereby granted, free of charge, to any person obtaining a copy
   8 # of this software and associated documentation files (the "Software"), to deal
   9 # in the Software without restriction, including without limitation the rights
  10 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 # copies of the Software, and to permit persons to whom the Software is
  12 # furnished to do so, subject to the following conditions:
  13 #
  14 # The above copyright notice and this permission notice shall be included in
  15 # all copies or substantial portions of the Software.
  16 #
  17 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23 # SOFTWARE.
  24 
  25 
  26 # last [options...] [max lines...] [files...]
  27 #
  28 # Limit output to only the last n given lines, using the leading number given,
  29 # or the last line by default. This is just more intuitive than using the
  30 # basic command `tail -n`.
  31 #
  32 # The only option available is to show this help message, using any of
  33 # `-h`, `--h`, `-help`, or `--help`, without the quotes.
  34 
  35 
  36 case "$1" in
  37     -h|--h|-help|--help)
  38         awk '/^# +last /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  39         exit 0
  40     ;;
  41 esac
  42 
  43 lines=1
  44 if echo "$1" | grep -q -E '^[+-]?[0-9]+$'; then
  45     lines="$1"
  46     shift
  47 fi
  48 
  49 [ "$1" = '--' ] && shift
  50 
  51 # show all non-existing files given
  52 failed=0
  53 for arg in "$@"; do
  54     if [ "${arg}" = "-" ]; then
  55         continue
  56     fi
  57     if [ ! -e "${arg}" ]; then
  58         printf "no file named \"%s\"\n" "${arg}" >&2
  59         failed=1
  60     fi
  61 done
  62 
  63 if [ "${failed}" -gt 0 ]; then
  64     exit 2
  65 fi
  66 
  67 tail -n "${lines}" "$@" | awk 1