color in shell

rgb.sh

#!/bin/bash

# rgb R G B
# 0 <= RGB <= 5
function rgb() {
	local R=$1 G=$2 B=$3
	echo -n $(( $R * 36 + $G * 6 + $B + 16 ))
}

test.sh

#!/bin/bash

function test1() {
	local R G B
	for R in 0 1 2 3 4 5 ; do
		for G in 0 1 2 3 4 5 ; do
			for B in 0 1 2 3 4 5 ; do
				printf "\e[48;5;$(rgb $R $G $B)m %3s " $(rgb $R $G $B)
			done
			echo -ne "\e[0m\n"
		done
		echo -ne "\e[0m\n"
	done
}

function p2() {
	local CARR=(00 5f 87 af d7 ff)
	echo -ne "\e[48;5;$(rgb $R $G $B)m        \e[0m"
	printf " - %3s " $(rgb $R $G $B)
	echo -e "($R, $G, $B) #${CARR[$R]}${CARR[$G]}${CARR[$B]}" 
}
function test2() {
	local I=16 R=5 G=0 B=0
	local GL=${1-"5"}
	local GH=$(( $GL - 1 ))
	for G in $(seq 0 $GL) ; do
		p2
	done
	for R in $(seq $GH -1 0) ; do
		p2
	done
	for B in $(seq 0 $GL) ; do
		p2
	done
	for G in $(seq $GH -1 0) ; do
		p2
	done
	for R in $(seq 0 $GL) ; do
		p2
	done
	for B in $(seq $GH -1 0) ; do
		p2
	done
}