scripts/colours.sh

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#!/usr/bin/env bash
# Print out escape sequences usable for coloured text on tty.
# shellcheck disable=2016
printf 'Colour escapes are %s\n' '\e[${value};...;${value}m'
printf 'Values 30..37 are \e[33mforeground colours\e[m\n'
printf 'Values 40..47 are \e[43mbackground colours\e[m\n'
printf 'Value 1 gives a \e[1mbold look\e[m\n'
printf 'Value 2 gives a \e[2mdim look\e[m\n'
printf 'Value 3 gives a \e[3mitalic look\e[m\n'
printf 'Value 4 gives a \e[4munderlined look\e[m\n'
printf 'Value 5 gives a \e[5mblinking look\e[m\n\n'
# foreground colours
for fgc in {30..37}; do
# background colours
for bgc in {40..47}; do
fgc=${fgc#37} # white
bgc=${bgc#40} # black
vals="${fgc:+$fgc};${bgc}"
vals=${vals%%;}
seq0="${vals:+\e[${vals}m}"
printf " %-9s" "${seq0:-(default)}"
echo -en " ${seq0}TEXT\e[m"
echo -en " \e[${vals:+${vals+$vals}};1mBOLD\e[m"
echo -en " \e[${vals:+${vals+$vals}};2mDIM\e[m"
echo -en " \e[${vals:+${vals+$vals}};3mITA\e[m"
echo -en " \e[${vals:+${vals+$vals}};4mUND\e[m"
echo -en " \e[${vals:+${vals+$vals}};5mBLI\e[m"
done
echo; echo
done
rainbowColor() {
local h=$(($1 / 43))
local f=$(($1 - 43 * h))
local t=$((f * 255 / 43))
local q=$((255 - t))
if [ $h -eq 0 ]
then
echo "255 $t 0"
elif [ $h -eq 1 ]
then
echo "$q 255 0"
elif [ $h -eq 2 ]
then
echo "0 255 $t"
elif [ $h -eq 3 ]
then
echo "0 $q 255"
elif [ $h -eq 4 ]
then
echo "$t 0 255"
elif [ $h -eq 5 ]
then
echo "255 0 $q"
else
# execution should never reach here
echo '0 0 0'
fi
}
rf(){ echo "$1" 0 0; }; gf(){ echo 0 "$1" 0; }; bf(){ echo 0 0 "$1"; }
for f in rf gf bf rainbowColor; do
for s in "$(seq 0 127)" "$(seq 255 -1 128)"; do
for i in $s; do
# shellcheck disable=2183,2046
printf '\x1b[48;2;%s;%s;%sm ' $($f "$i")
done
echo -en "\x1b[0m\n"
done
done