Print all the xterm colors

colorsxterm.sh

#! /usr/bin/env bash

# print all the xterm colors
# see http://serverfault.com/a/91873 about caculating the rgb values


for c in {0..15}
do
  printf "\033[38;5;%dm %2d" $c $c
  if (( (c+1) % 8 == 0 )) ; then
    echo
  fi
done

for r in {0..5}
do
  for g in {0..5}
  do
    for b in {0..5}
    do
      (( rgb = (36 * $r) + (6 * $g) + $b + 16))
      (( nrgb = rgb - 16 ))
      printf "\033[38;5;%dm (%3d) %d %d %d" $rgb $rgb $r $g $b
      if (( (nrgb+1) % 6 == 0 )) ; then
        echo
      fi
      if (( g == 5 &&  b == 5 )) ; then
        echo
      fi
    done
  done
done

for c in {232..255}
do
  printf "\033[38;5;%dm %2d" $c $c
  if (( (c+1) % 8 == 0 )) ; then
    echo
  fi
done