File: avoid.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 # avoid [options...] [regular expressions...]
  27 #
  28 # Avoid/ignore lines which match any of the extended-mode regular expressions
  29 # given. When not given any regex, all empty lines are ignored by default.
  30 #
  31 # Input lines always come from the standard input.
  32 #
  33 # The options are, available both in single and double-dash versions
  34 #
  35 #   -h, -help     show this help message
  36 #   -i, -ins      match regexes case-insensitively
  37 #   -q, -quiet    never emit output: exit code still succeeds/fails
  38 
  39 
  40 buffered=0
  41 insensitive=0
  42 quiet=0
  43 
  44 while [ $# -gt 0 ]; do
  45     case "$1" in
  46         -b|--b|-buffered|--buffered) buffered=1; shift; continue ;;
  47 
  48         -h|--h|-help|--help)
  49             awk '/^# +avoid /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  50             exit 0
  51         ;;
  52 
  53         -i|--i|-ins|--ins|-insensitive|--insensitive)
  54             insensitive=1
  55             shift
  56             continue
  57         ;;
  58 
  59         -q|--q|-quiet|--quiet)
  60             quiet=1
  61             shift
  62             continue
  63         ;;
  64 
  65         --) shift; break ;;
  66 
  67         -*)
  68             printf "unsupported option '%s'\n" "$1" >&2
  69             exit 1
  70         ;;
  71     esac
  72 
  73     break
  74 done
  75 
  76 if [ "${quiet}" -eq 1 ]; then
  77     buffered=1
  78 fi
  79 
  80 flush=0
  81 if [ "${buffered}" -eq 0 ] && { [ -p /dev/stdout ] || [ -t 1 ]; }; then
  82     flush=1
  83 fi
  84 
  85 awk -v flush="${flush}" -v ci="${insensitive}" -v quiet="${quiet}" '
  86     BEGIN {
  87         if (ci && IGNORECASE == "") {
  88             msg = "this variant of AWK lacks case-insensitive regex-matching"
  89             print(msg) > "/dev/stderr"
  90             exit 125
  91         }
  92         if (ci) IGNORECASE = 1
  93 
  94         for (i = 1; i < ARGC; i++) {
  95             re[i] = ARGV[i]
  96             delete ARGV[i]
  97         }
  98 
  99         if (quiet) flush = 0
 100     }
 101 
 102     {
 103         plain = $0
 104         gsub(/\x1b\[([0-9]{4,}[A-Za-z])/, "", plain)
 105 
 106         for (i = 1; i < ARGC; i++) if (plain ~ re[i]) next
 107         if (!quiet) print
 108         if (flush) fflush()
 109         got++
 110     }
 111 
 112     END { exit(got == 0) }
 113 ' "${@:-^\r?$}"