File: sbs.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 # sbs [column count...] [files...]
  27 #
  28 # Side-By-Side lays out lines read from all inputs given into several columns,
  29 # separating them with a special symbol. If no named inputs are given, lines
  30 # are read from the standard input, instead of files.
  31 #
  32 # If a column-count isn't given, the script tries to find the most columns
  33 # which can fit a reasonable width-limit; when even a single column can't fit
  34 # that limit, it simply emits all lines, which is the same as using 1 column.
  35 
  36 
  37 case "$1" in
  38     -h|--h|-help|--help)
  39         awk '/^# +sbs /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  40         exit 0
  41     ;;
  42 esac
  43 
  44 num_columns=0
  45 if echo "$1" | grep -q -E '^[+-]?[0-9]+$'; then
  46     num_columns="$1"
  47     shift
  48 fi
  49 
  50 fancy_sep=1
  51 case "$1" in
  52     -no-sep|--no-sep|-s|--s|-simple|--simple)
  53         fancy_sep=0
  54         shift
  55     ;;
  56 esac
  57 
  58 [ "$1" = '--' ] && shift
  59 
  60 # show all non-existing files given
  61 failed=0
  62 for arg in "$@"; do
  63     if [ "${arg}" = "-" ]; then
  64         continue
  65     fi
  66     if [ ! -e "${arg}" ]; then
  67         printf "\e[38;2;204;0;0mno file named \"%s\"\e[0m\n" "${arg}" >&2
  68         failed=1
  69     fi
  70 done
  71 
  72 # in case of errors, avoid showing an empty screen
  73 if [ "${failed}" -gt 0 ]; then
  74     exit 2
  75 fi
  76 
  77 # allow loading lines from multiple files, ensuring no lines are accidentally
  78 # joined across inputs
  79 awk 1 "$@" |
  80 
  81 # ignore leading UTF-8 BOMs (byte-order marks) and trailing carriage-returns:
  82 # the latter in particular will ruin side-by-side output; doing it separately
  83 # using `sed` is faster overall for the script
  84 sed 's-^\xef\xbb\xbf--; s-\r$--' |
  85 
  86 # before laying out lines side-by-side, expand all tabs, using 4 as the
  87 # tabstop width
  88 expand -t 4 |
  89 
  90 # lay lines into side-by-side columns
  91 awk -v fancy="${fancy_sep}" -v num_columns="${num_columns}" '
  92     BEGIN {
  93         sep = fancy ? " █" : " "
  94         sep_width = width(sep)
  95         total_max_width = 79
  96         max_auto_cols = 26
  97 
  98         # num_columns = 0
  99         # detect a leading number, and use it as the max-number of columns
 100         if (ARGV[1] + 0 != 0) {
 101             num_columns = ARGV[1] + 0
 102             delete ARGV[1]
 103         }
 104     }
 105 
 106     # remember all lines; carriage-returns are already removed
 107     { lines[NR] = $0 }
 108 
 109     # width counts items in the string given, ignoring ANSI-style sequences
 110     function width(s) {
 111         gsub(/\x1b\[[0-9;]*[A-Za-z]/, "", s)
 112         return length(s)
 113     }
 114 
 115     # pick a line using a row-column pair as an index
 116     function pick(lines, height, row, col) {
 117         return lines[(col - 1) * height + row]
 118     }
 119 
 120     # see if a list of lines can fit the number of columns given exactly
 121     function fits(lines, line_count, num_cols, height, max_widths, i, j, w, l) {
 122         height = ceil(line_count / num_cols)
 123 
 124         # prevent too many empty columns
 125         if (height * num_cols - line_count >= height) {
 126             return 0
 127         }
 128 
 129         for (i = 1; i <= height; i++) {
 130             for (j = 1; j <= num_cols; j++) {
 131                 w = width(pick(lines, height, i, j))
 132                 if (w > total_max_width) return 0
 133                 if (max_widths[j] < w) max_widths[j] = w
 134             }
 135         }
 136 
 137         for (i = 1; i <= height; i++) {
 138             w = 0
 139 
 140             for (j = 1; j <= num_cols; j++) {
 141                 if (j > 1) w += sep_width
 142 
 143                 l = pick(lines, height, i, j)
 144                 if (j > 1 && l != "") w++
 145 
 146                 w += width(l)
 147 
 148                 if (j < num_cols) {
 149                     pad = max_widths[j] - width(l)
 150                     if (pad > 0) {
 151                         if (l == "") pad++
 152                         w += pad
 153                     }
 154                 }
 155 
 156                 if (w > total_max_width) return 0
 157             }
 158         }
 159 
 160         return 1
 161     }
 162 
 163     # auto-detect an appropriate column-count for the list of lines given
 164     function find_max_fit(lines, num_columns) {
 165         if (!fits(lines, NR, 1)) {
 166             return 1
 167         }
 168 
 169         for (num_columns = max_auto_cols; num_columns >= 2; num_columns--) {
 170             if (fits(lines, NR, num_columns)) {
 171                 return num_columns
 172             }
 173         }
 174         return 1
 175     }
 176 
 177     # round up non-integers
 178     function ceil(n) {
 179         return (n % 1) ? n - (n % 1) + 1 : n
 180     }
 181 
 182     END {
 183         # prevent errors when input has no lines
 184         if (NR < 1) exit
 185 
 186         # auto-fit when given a non-positive count, or when not given a count
 187         if (num_columns < 1) num_columns = find_max_fit(lines)
 188 
 189         # prevent column-count from exceeding the number of input lines
 190         if (num_columns > NR) num_columns = NR
 191 
 192         # emit a single column as lines, quitting right away
 193         if (num_columns < 2) {
 194             for (i = 1; i <= NR; i++) print lines[i]
 195             exit
 196         }
 197 
 198         # prevent a trailing empty column
 199         num_lines = ceil(NR / num_columns)
 200         if (num_lines * num_columns - NR >= num_lines) {
 201             num_columns--
 202         }
 203 
 204         num_lines = ceil(NR / num_columns)
 205         for (i = 1; i <= num_lines; i++) {
 206             for (j = 1; j <= num_columns; j++) {
 207                 w = width(pick(lines, num_lines, i, j))
 208                 if (max_widths[j] < w) max_widths[j] = w
 209             }
 210         }
 211 
 212         widest = 0
 213         for (i in max_widths) {
 214             if (widest < max_widths[i]) widest = max_widths[i]
 215         }
 216 
 217         # emit lines side by side
 218         for (i = 1; i <= num_lines; i++) {
 219             for (j = 1; j <= num_columns; j++) {
 220                 l = pick(lines, num_lines, i, j)
 221 
 222                 if (j > 1) {
 223                     printf "%s", sep
 224                     if (j != num_columns || l != "") printf " "
 225                 }
 226 
 227                 printf "%s", l
 228 
 229                 if (j < num_columns) {
 230                     pad = max_widths[j] - width(l)
 231                     if (pad > 0) printf "%*s", pad, ""
 232                 }
 233             }
 234 
 235             print ""
 236         }
 237     }
 238 ' |
 239 
 240 # view the result interactively, if possible
 241 { less -MKiCRS 2> /dev/null || cat; }