File: bsbs.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 # bsbs [column count...] [files...]
  27 #
  28 #
  29 # Book-like Side-By-Side lays out text lines into several columns, separating
  30 # them with a special symbol. This script lets you see more data at once, as
  31 # monitors are wider than tall and most text content has fairly short lines.
  32 #
  33 # If a column-count isn't given, it's 2 by default, just like with books. If
  34 # no named inputs are given, lines are read from the standard input.
  35 #
  36 # Hint: you can make handy aliases for this tool
  37 #
  38 # alias 1='bsbs 1'
  39 # alias 2='bsbs 2'
  40 # alias 3='bsbs 3'
  41 # alias 4='bsbs 4'
  42 # alias 5='bsbs 5'
  43 # alias 6='bsbs 6'
  44 # alias 7='bsbs 7'
  45 # alias 8='bsbs 8'
  46 # alias 9='bsbs 9'
  47 
  48 
  49 case "$1" in
  50     -h|--h|-help|--help)
  51         awk '/^# +bsbs /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  52         exit 0
  53     ;;
  54 esac
  55 
  56 if [ $# -eq 0 ] && [ ! -p /dev/stdin ]; then
  57     awk '/^# +bsbs /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  58     printf "\e[38;2;204;0;0mno files given and stdin not being piped\e[0m\n"
  59     exit 0
  60 fi
  61 
  62 num_columns=2
  63 if echo "$1" | grep -q -E '^[+-]?[0-9]+$'; then
  64     num_columns="$1"
  65     shift
  66 fi
  67 
  68 [ "$1" = '--' ] && shift
  69 
  70 if [ "${num_columns}" -lt 1 ]; then
  71     num_columns=1
  72 fi
  73 
  74 # use the current screen height
  75 height="$(tput -T xterm lines)"
  76 
  77 if [ "${height}" -lt 2 ]; then
  78     printf "\e[38;2;204;0;0mscreen/window is too short\e[0m\n" >&2
  79     exit 1
  80 fi
  81 
  82 # show all non-existing files given
  83 failed=0
  84 for arg in "$@"; do
  85     if [ "${arg}" = "-" ]; then
  86         continue
  87     fi
  88     if [ ! -e "${arg}" ]; then
  89         printf "\e[38;2;204;0;0mno file named \"%s\"\e[0m\n" "${arg}" >&2
  90         failed=1
  91     fi
  92 done
  93 
  94 # in case of errors, avoid showing an empty screen
  95 if [ "${failed}" -gt 0 ]; then
  96     exit 2
  97 fi
  98 
  99 # allow loading lines from multiple files, ensuring no lines are accidentally
 100 # joined across inputs
 101 awk 1 "$@" |
 102 
 103 # ignore leading UTF-8 BOMs (byte-order marks) and trailing carriage-returns:
 104 # the latter in particular will ruin side-by-side output; doing it separately
 105 # using `sed` is faster overall for the script
 106 sed 's-^\xef\xbb\xbf--; s-\r$--' |
 107 
 108 # before laying out lines side-by-side, expand all tabs
 109 expand -t 4 |
 110 
 111 # lay things side-by-side, like pages/faces in a book
 112 awk -v num_columns="${num_columns}" -v height="${height}" '
 113     BEGIN {
 114         inner_rows = height - 2
 115     }
 116 
 117     # remember all lines; assumes carriage-returns are already removed
 118     {
 119         p = NR - 1
 120         lines[p] = $0
 121         gsub(/\x1b\[[0-9;]*[A-Za-z]/, "")
 122         widths[p] = length($0)
 123     }
 124 
 125     # round up non-integers
 126     function ceil(n) {
 127         return (n % 1) ? n - (n % 1) + 1 : n
 128     }
 129 
 130     END {
 131         # if a single column is enough for all lines, just show lines as given
 132         if (NR <= inner_rows) {
 133             for (i = 0; i < NR; i++) print lines[i]
 134             exit
 135         }
 136 
 137         # avoid empty trailing columns
 138         if (NR < inner_rows * num_columns) num_columns = ceil(NR / inner_rows)
 139         # ensure number of columns is valid
 140         if (num_columns < 1) num_columns = 1
 141 
 142         for (i = 0; i < NR; i += inner_rows * num_columns) {
 143             for (j = 0; j < inner_rows; j++) {
 144                 for (k = 0; k < num_columns; k++) {
 145                     w = widths[i + k * inner_rows + j]
 146                     if (max_widths[k] < w) max_widths[k] = w
 147                 }
 148             }
 149         }
 150 
 151         widest = 0
 152         for (i in max_widths) {
 153             if (widest < max_widths[i]) widest = max_widths[i]
 154         }
 155 
 156         total_max_width = 0
 157         for (i = 0; i < num_columns; i++) {
 158             total_max_width += max_widths[i]
 159         }
 160         # also count separators, which are 3-items wide
 161         if (num_columns > 0) total_max_width += 3 * (num_columns - 1)
 162 
 163         # make a separator wide enough to match the length of any output line
 164         bottom_sep = "································"
 165         for (nsep = 32; nsep < total_max_width; nsep *= 2) {
 166             bottom_sep = bottom_sep bottom_sep
 167         }
 168         # separator is used directly, so match the needed width exactly
 169         bottom_sep = substr(bottom_sep, 1, total_max_width)
 170 
 171         # emit lines side by side
 172         for (i = 0; i < NR; i += inner_rows * num_columns) {
 173             # emit a page-bottom/separator line between pages of columns
 174             if (i > 0) print bottom_sep
 175 
 176             for (j = 0; j < inner_rows; j++) {
 177                 # bottom-pad last page-pair with empty lines, so page-scrolling
 178                 # on viewers like `less` stays in sync with the page boundaries
 179                 if (NR - i - j <= 0) {
 180                     print ""
 181                     continue
 182                 }
 183 
 184                 for (k = 0; k < num_columns; k++) {
 185                     p = i + k * inner_rows + j
 186                     l = lines[p]
 187 
 188                     if (k > 0) {
 189                         printf "\x1b[0m █"
 190                         if (k != num_columns - 1 || l != "") printf " "
 191                     }
 192 
 193                     printf "%s", l
 194 
 195                     if (k < num_columns - 1) {
 196                         pad = max_widths[k] - widths[p]
 197                         if (pad > 0) printf "%*s", pad, ""
 198                     }
 199                 }
 200 
 201                 print "\x1b[0m"
 202             }
 203         }
 204 
 205         # end last page with an empty line, instead of the usual page-separator
 206         if (NR > 0) print ""
 207     }
 208 ' |
 209 
 210 # view the result interactively
 211 less -MKiCRS