Displays all the bash colors to the screen

bash_colors.sh

### Bash colors and formatting

# To set the formatting/color, use the following:
#   - escape character (\e, \033, \x1B)
#   - open square bracket
#   - attributes (semicolon-separated)
#   - the letter m
#
#   \033[<attribute>;...m

### FORMATTING (+20 resets the value)
# 0  Reset all formatting
# 1  Bold
# 2  Dimmed foreground
# 4  Underscore
# 5  Blink
# 7  Invert fg/bg colors
# 8  Hide text

### COLORS
#              Dark | Bright
# Foreground:   +30 | +90
# Background:   +40 | +100
#
# 0           Black | Gray
# 1                Red
# 2               Green
# 3               Yellow
# 4                Blue
# 5               Purple
# 6                Cyan
# 7            Gray | White
# 9         Default | Not available



#   This file echoes a bunch of color codes to the 
#   terminal to demonstrate what's available.  Each 
#   line is the color code of one forground color,
#   out of 17 (default + 16 escapes), followed by a 
#   test use of that color on all nine background 
#   colors (default + 8 escapes).

T='gYw'   # The test text

echo -e "\n                 40m     41m     42m     43m\
     44m     45m     46m     47m";

for FGs in '    m' '   1m' '  30m' '1;30m' '  31m' '1;31m' '  32m' \
           '1;32m' '  33m' '1;33m' '  34m' '1;34m' '  35m' '1;35m' \
           '  36m' '1;36m' '  37m' '1;37m';
  do FG=${FGs// /}
  echo -en " $FGs \033[$FG  $T  "
  for BG in 40m 41m 42m 43m 44m 45m 46m 47m;
    do echo -en "$EINS \033[$FG\033[$BG  $T  \033[0m";
  done
  echo;
done
echo



#Another way:
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"

sample='bash'

# 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 " ${seq0}${sample}\e[m"
    printf " \e[${vals:+${vals+$vals;}}1mBOLD\e[m"
  done

  echo; echo
done

Source: http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x329.html