File: vn.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 # vn [options...] [files...]
  27 #
  28 # View with line Numbers, which runs `less -~MKNiCRS`, for an interactive text
  29 # viewer with both horizontal and vertical scrolling, line numbers on the side,
  30 # ANSI-code support for styled/colored text, and case-insensitive regex search.
  31 #
  32 # If `less` is a symbolic-link, it's assumed to point to `busybox`, and
  33 # (for compatibility) `less -~NRIMS` is run instead.
  34 #
  35 # The options are, available both in single and double-dash versions
  36 #
  37 #   -h, -help            show this help message
  38 #   --header=N           always show first N lines on top; may fail
  39 #   -sticky, -t, -top    same as option `--header=1`; may fail
  40 
  41 
  42 # busybox's `less` doesn't support the options `-C` and `-K`
  43 if [ -L less ]; then
  44     options='-~NRIMS'
  45 else
  46     options='-~MKNiCRS'
  47 fi
  48 
  49 while [ $# -gt 0 ]; do
  50     case "$1" in
  51         -f|--f) options="${options} -f"; shift; continue ;;
  52 
  53         -h|--h|-help|--help)
  54             awk '/^# +vn /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  55             exit 0
  56         ;;
  57 
  58         --header=*) options="${options} $1"; shift; continue ;;
  59 
  60         -sticky|--sticky|-t|--t|-top|--top)
  61             options="${options} --header=1"; shift; continue
  62         ;;
  63 
  64         -) break ;;
  65 
  66         --) shift; break ;;
  67 
  68         -*)
  69             printf "%s: unsupported option %s\n" "$0" "$1" >&2
  70             exit 1
  71         ;;
  72     esac
  73 
  74     break
  75 done
  76 
  77 if [ $# -gt 0 ] || [ -p /dev/stdin ]; then
  78     less ${options} "$@"
  79 else
  80     awk '/^# +vn /, /^$/ { gsub(/^# ?/, ""); print }' "$0" >&2
  81     exit 1
  82 fi