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:

PS1='\[\033[1;31m\]\$\[\033[0;37m\] '

rainbow:

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:

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.