File: center.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 # center [options...] [width...] [files...]
  27 #
  28 # CENTER-align lines of text, using the (optional) width given and the widest
  29 # line from the input(s). If given a valid number, it's used as the width, or
  30 # the current window width is used by default.
  31 #
  32 # The options are, available both in single and double-dash versions
  33 #
  34 #    -h, -help    show this help message
  35 
  36 
  37 case "$1" in
  38     -h|--h|-help|--help)
  39         awk '/^# +center /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  40         exit 0
  41     ;;
  42 esac
  43 
  44 width=80
  45 if echo "$1" | grep -q -E '^[0-9]+$'; then
  46     width="$1"
  47     shift
  48 else
  49     width="$(tput -T xterm cols 2> /dev/null || echo 80)"
  50 fi
  51 
  52 [ "$1" = '--' ] && shift
  53 
  54 # center-align lines of text, using the current screen width
  55 awk -v width="${width}" '
  56     {
  57         gsub(/\r$/, "")
  58         lines[NR] = $0
  59 
  60         plain = $0
  61         gsub(/\x1b\[[0-9;]*[A-Za-z]/, "", plain)
  62         l = length(plain)
  63         if (maxlen < l) maxlen = l
  64     }
  65 
  66     END {
  67         n = (width - maxlen) / 2
  68         if (n % 1) n = n - (n % 1)
  69         if (n < 1) n = 80
  70         fmt = sprintf("%%%ds%%s\n", (n > 0) ? n : 0)
  71         for (i = 1; i <= NR; i++) printf fmt, "", lines[i]
  72     }
  73 ' "$@"