quick'n'dirty underline rendering test

underline.sh

#! /bin/bash

function ul_color1() {
    echo -ne "\033[58:2:255:250:32m"
}

function ul_color2() {
    echo -ne "\033[58:2:255:32:32m"
}

function ul_color3() {
    echo -ne "\033[58:2:32:255:32m"
}

ul_color1
echo -ne "\033[4m Underline Normal As Usual\033[mEnd\n"
ul_color2
echo -ne "\033[21m Underline $(ul_color3)Doubly As Usual\033[mEnd\n"
echo -ne "\033[4mXUnderlineXNormalxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx \033[mEnd\n"
for i in 0 1 2 3 4 5 6; do
    echo -ne "\033[58:2:$[i * 40]:250:250m"
    echo -ne "\033[4:${i}m Underline ${i} \033[mEnd\n"
done