File: nullines.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 # nullines [options...] [files...]
  27 #
  28 # NUL-terminated LINES ends each line with a Zero/null byte, instead of the
  29 # usual line-feed byte. Unlike `cat`, this tool ensures no lines across inputs
  30 # are accidentally joined, since all lines it outputs end with a null byte,
  31 # even when the original files don't have a final line-feed byte.
  32 #
  33 # The options are, available both in single and double-dash versions
  34 #
  35 #   -h, -help    show this help message
  36 
  37 
  38 buffered=0
  39 
  40 case "$1" in
  41     -b|--b|-buffered|--buffered) buffered=1; shift ;;
  42 
  43     -h|--h|-help|--help)
  44         awk '/^# +nullines /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  45         exit 0
  46     ;;
  47 
  48     -) ;;
  49 
  50     --) shift ;;
  51 
  52     -*)
  53         printf "%s: unsupported option '%s'\n" "$0" "$1" >&2
  54         exit 1
  55     ;;
  56 esac
  57 
  58 # show all non-existing files given
  59 failed=0
  60 for arg in "$@"; do
  61     [ "${arg}" = "-" ] && continue
  62     [ -e "${arg}" ] && continue
  63     printf "%s: no file named \"%s\"\n" "$0" "${arg}" >&2
  64     failed=1
  65 done
  66 
  67 [ "${failed}" -gt 0 ] && exit 2
  68 
  69 flush=0
  70 if [ "${buffered}" -eq 0 ] && { [ -p /dev/stdout ] || [ -t 1 ]; }; then
  71     flush=1
  72 fi
  73 
  74 awk -v flush="${flush}" '
  75     FNR == 1 { gsub(/^\xef\xbb\xbf/, "") }
  76 
  77     {
  78         printf("%s\000", $0)
  79         if (flush) fflush()
  80     }
  81 ' "$@"