# colors in terminals

escape in ascii is `27` (decimal), `\033` (octal), `\x1b` (hex).
not all shells seem to support all of it, f.e. in my case hex doesn't work.
some shells support `\e`. escape followed by a `[` introduces a *csi sequence*,
ended by `m` the csi sequence changes character appearance.

`\e[xm` while `x` is semicolon seperated list of:
- `0` normal (default), `1` bold ...
- `30-37` foreground colors
- `40-47` background colors

to get proper line breaks notify shell that chars are non-printable (zero width)
by wrapping them in `\[` and `\]`.


## examples

normal green: `echo -e "\033[0;32mnormal green"`

`PS1` with bold red prompt, default white stdin and working linebreak:
```bash
PS1='\[\033[1;31m\]\$\[\033[0;37m\] '
```

rainbow:
```sh
for (( i = 30; i < 38; i++ )); do
    echo -e "\033[0;"$i"m Normal: (0;$i); \033[1;"$i"m Light: (1;$i)";
done
```

table, taken from manjaros `.bashrc`:
```sh
colors() {
	local fgc bgc vals seq0

	printf "Color escapes are %s\n" '\e[${value};...;${value}m'
	printf "Values 30..37 are \e[33mforeground colors\e[m\n"
	printf "Values 40..47 are \e[43mbackground colors\e[m\n"
	printf "Value  1 gives a  \e[1mbold-faced look\e[m\n\n"

	# foreground colors
	for fgc in {30..37}; do
		# background colors
		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)}"
			printf " ${seq0}TEXT\e[m"
			printf " \e[${vals:+${vals+$vals;}}1mBOLD\e[m"
		done
		echo; echo
	done
}
```


## errata

does `1` mean `bold` or `light`? i have confusing terminology here.