rc/sh/colors2

#!/usr/bin/env bash
# compat: +ash +bash +dash +hush +ksh +mksh +oksh +osh +posh +yash +zsh

colors2() {
    [ $# -eq 0 ] || { printf "%s\n" "$0: does not take arguments" >&2; return 1; }
    local a= b= i= j=
    for a in 0 60; do
        for j in 40 41 43 42 46 44 45 47; do
            printf ' \033[%s;%sm %03d \033[m' '48;5;16' $((a+j-10)) $((a+j))
        done
        printf '\n'

        for b in 0 60; do
            for i in 30 31 33 32 36 34 35 37; do
                for j in 40 41 43 42 46 44 45 47; do
                    printf ' \033[%s;%sm %03d \033[m' $((a+j)) $((b+i)) $((b+i))
                done
                printf '\n'
            done
        done
        [ $a = 0 ] && printf '\n'
    done
}

[ -n "${preload+-}" ] || colors2 "$@"