File: stomp.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 # stomp [options...] [files...]
  27 #
  28 # Turn runs of empty lines into single empty lines, effectively squeezing
  29 # paragraphs vertically, so to speak; runs of empty lines both at the start
  30 # and at the end are completely ignored.
  31 #
  32 # This script also ensures no lines across inputs are accidentally joined,
  33 # since all lines it outputs end with line-feeds, even when the original
  34 # files don't.
  35 #
  36 # The options are, available both in single and double-dash versions
  37 #
  38 #   -h, -help    show this help message
  39 
  40 
  41 buffered=0
  42 
  43 case "$1" in
  44     -b|--b|-buffered|--buffered)
  45         buffered=1
  46         shift
  47     ;;
  48 
  49     -h|--h|-help|--help)
  50         awk '/^# +stomp /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  51         exit 0
  52     ;;
  53 
  54     -) ;;
  55 
  56     --) shift ;;
  57 
  58     -*)
  59         printf "unsupported option '%s'\n" "$1" >&2
  60         exit 1
  61     ;;
  62 esac
  63 
  64 # show all non-existing files given
  65 failed=0
  66 for arg in "$@"; do
  67     [ "${arg}" = "-" ] && continue
  68     [ -e "${arg}" ] && continue
  69     printf "no file named \"%s\"\n" "${arg}" >&2
  70     failed=1
  71 done
  72 
  73 [ "${failed}" -gt 0 ] && exit 2
  74 
  75 flush=0
  76 if [ "${buffered}" -eq 0 ] && { [ -p /dev/stdout ] || [ -t 1 ]; }; then
  77     flush=1
  78 fi
  79 
  80 awk -v flush="${flush}" '
  81     /^\r?$/ { empty = 1; next }
  82     empty { empty = 0; if (n > 0) print "" }
  83     { n++; print; if (flush) fflush() }
  84 ' "$@"