File: leak.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 # leak [options...] [style name...] [files...]
  27 #
  28 # Emit copies of input lines both to stdout and to stderr, thus `leaking`
  29 # the contents going through a pipe of commands, using the leading argument
  30 # as the style/color name to use to decorate the stderr output.
  31 #
  32 # This tool's main use-case is to inspect/debug the intermediate stages of a
  33 # `pipelined` shell command.
  34 #
  35 # When variable NO_COLOR is declared and set to 1, an invert/highlight style
  36 # is used instead of colors.
  37 #
  38 # The options are, available both in single and double-dash versions
  39 #
  40 #   -h, -help    show this help message
  41 #
  42 # Supported style names include
  43 #
  44 # - red     - orange    - bold     - underline
  45 # - green   - magenta   - purple   - invert
  46 # - blue    - gray      - italic
  47 #
  48 # Supported aliases for style names include
  49 #
  50 #   b    (blue)              bb    (blue background)
  51 #   g    (green)             gb    (green background)
  52 #   h    (hilight/invert)
  53 #   m    (magenta)           mb    (magenta background)
  54 #   o    (orange)            ob    (orange background)
  55 #   p    (purple)            pb    (purple background)
  56 #   r    (red)               rb    (red background)
  57 #   u    (underline)
  58 
  59 
  60 buffered=0
  61 
  62 case "$1" in
  63     -b|--b|-buffered|--buffered)
  64         buffered=1
  65         shift
  66     ;;
  67 
  68     -h|--h|-help|--help)
  69         awk '/^# +leak /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  70         exit 0
  71     ;;
  72 
  73     --) ;;
  74 
  75     -*)
  76         printf "unsupported option '%s'\n" "$1" >&2
  77         exit 1
  78     ;;
  79 esac
  80 
  81 name="$(echo "${1:-gray}" | sed 's/^--?//')"
  82 [ $# -gt 0 ] && shift
  83 
  84 [ "$1" = '--' ] && shift
  85 
  86 # show all non-existing files given
  87 failed=0
  88 for arg in "$@"; do
  89     [ "${arg}" = "-" ] && continue
  90     [ -e "${arg}" ] && continue
  91     printf "no file named \"%s\"\n" "${arg}" >&2
  92     failed=1
  93 done
  94 
  95 [ "${failed}" -gt 0 ] && exit 2
  96 
  97 flush=0
  98 if [ "${buffered}" -eq 0 ] && { [ -p /dev/stdout ] || [ -t 1 ]; }; then
  99     flush=1
 100 fi
 101 
 102 if [ "${NO_COLOR}" = 1 ]; then
 103     name='inverse'
 104 fi
 105 
 106 # handle special style-names
 107 case "${name}" in
 108     plain)
 109         # the long AWK script can't handle simply removing all styles
 110         awk -v flush="${flush}" '
 111             {
 112                 print
 113                 if (flush) fflush()
 114                 gsub(/\x1b\[[0-9;]*[A-Za-z]/, "")
 115                 print > "/dev/stderr"
 116             }
 117         ' "$@"
 118         exit $?
 119     ;;
 120 
 121     keep|same)
 122         awk -v flush="${flush}" '
 123             {
 124                 print
 125                 if (flush) fflush()
 126                 print > "/dev/stderr"
 127             }
 128         ' "$@"
 129         exit $?
 130     ;;
 131 esac
 132 
 133 # general case to handle actual styles
 134 awk -v flush="${flush}" -v name="${name}" '
 135     BEGIN {
 136         # pick a default style, when no style is given
 137         if (name == "") name = "gray"
 138         orig = name
 139         gsub(/^-{1,2}/, "", name)
 140 
 141         # alias-lookup table
 142         a["r"] = "red"
 143         a["g"] = "green"
 144         a["b"] = "blue"
 145         a["o"] = "orange"
 146         a["p"] = "purple"
 147         a["m"] = "magenta"
 148         a["h"] = "invert"
 149         a["i"] = "invert"
 150         a["u"] = "underline"
 151         a["or"] = "orange"
 152         a["ma"] = "magenta"
 153         a["hi"] = "invert"
 154         a["in"] = "invert"
 155         a["un"] = "underline"
 156         a["inv"] = "invert"
 157         a["mag"] = "magenta"
 158         a["grey"] = "gray"
 159         a["inverse"] = "invert"
 160         a["inverted"] = "invert"
 161         a["hilite"] = "invert"
 162         a["hilited"] = "invert"
 163         a["highlight"] = "invert"
 164         a["highlighted"] = "invert"
 165         a["underlined"] = "underline"
 166         a["bb"] = "blueback"
 167         a["gb"] = "greenback"
 168         a["mb"] = "magentaback"
 169         a["ob"] = "orangeback"
 170         a["pb"] = "purpleback"
 171         a["rb"] = "redback"
 172         a["bg"] = "greenback"
 173         a["bm"] = "magentaback"
 174         a["bo"] = "orangeback"
 175         a["bp"] = "purpleback"
 176         a["br"] = "redback"
 177         a["bluebg"] = "blueback"
 178         a["graybg"] = "grayback"
 179         a["greenbg"] = "greenback"
 180         a["greyback"] = "grayback"
 181         a["greybg"] = "grayback"
 182         a["magentabg"] = "magentaback"
 183         a["orangebg"] = "orangeback"
 184         a["purplebg"] = "purpleback"
 185         a["redbg"] = "redback"
 186         a["magback"] = "magentaback"
 187         a["magbg"] = "magentaback"
 188         a["orback"] = "orangeback"
 189         a["orbg"] = "orangeback"
 190         a["purback"] = "purpleback"
 191         a["purbg"] = "purpleback"
 192 
 193         # style-lookup table
 194         s["red"] = "\x1b[38;2;204;0;0m"
 195         s["green"] = "\x1b[38;2;0;135;95m"
 196         s["blue"] = "\x1b[38;2;0;95;215m"
 197         s["orange"] = "\x1b[38;2;215;95;0m"
 198         s["purple"] = "\x1b[38;2;135;95;255m"
 199         s["magenta"] = "\x1b[38;2;215;0;255m"
 200         s["gray"] = "\x1b[38;2;168;168;168m"
 201         s["bold"] = "\x1b[1m"
 202         s["invert"] = "\x1b[7m"
 203         s["italic"] = "\x1b[3m"
 204         s["underline"] = "\x1b[4m"
 205         s["blueback"] = "\x1b[48;2;0;95;215m\x1b[38;2;238;238;238m"
 206         s["grayback"] = "\x1b[48;2;168;168;168m\x1b[38;2;238;238;238m"
 207         s["greenback"] = "\x1b[48;2;0;135;95m\x1b[38;2;238;238;238m"
 208         s["magentaback"] = "\x1b[48;2;215;0;255m\x1b[38;2;238;238;238m"
 209         s["orangeback"] = "\x1b[48;2;215;95;0m\x1b[38;2;238;238;238m"
 210         s["purpleback"] = "\x1b[48;2;135;95;255m\x1b[38;2;238;238;238m"
 211         s["redback"] = "\x1b[48;2;204;0;0m\x1b[38;2;238;238;238m"
 212 
 213         # resolve aliases
 214         if (a[name] != "") name = a[name]
 215 
 216         # handle unsupported style-names with an error
 217         if (s[name] == "") {
 218             fmt = "unsupported style/color name `%s`\n"
 219             printf fmt, orig > "/dev/stderr"
 220             exit 1
 221         }
 222 
 223         # match ANSI-code to the name
 224         style = s[name]
 225     }
 226 
 227     # leak (re)styled lines to stderr
 228     {
 229         print
 230         if (flush) fflush()
 231         gsub(/\x1b\[[0-9;]*[A-Za-z]/, "")
 232         printf "%s%s\x1b[0m\n", style, $0 > "/dev/stderr"
 233     }
 234 ' "$@"