echolor 
Echo with colour, meant for your command line.
Wait what, does this really need to be a gem?
No, you're right. It doesn't. Adding the following snippet to your .bashrc would perfectly replicate what this gem does.
(Full list of color codes shared here)
COLOUR_CODE_BLUE='\033[0;34m'
COLOUR_CODE_NC='\033[0m'
function echolor() {
upcase=$(echo $1 | awk '{print toupper($0)}')
code="COLOUR_CODE_$upcase"
echo -e "${!code}${@:2}${COLOUR_CODE_NC}"
}But that's a mouthful, and not easy to share. It's far easier to use a package manager to install a gem that gives you an executable for use on your command line. I also thought this would be a nice way to learn how Ruby testing for executables works.
Installation
gem install echolor
Usage
$> echolor -h
Usage: echolor [options] [color] [text]
Available option(s):
-n Skips newline
Available colors:
black
light_black
red
light_red
green
light_green
yellow
light_yellow
blue
light_blue
magenta
light_magenta
cyan
light_cyan
white
light_white
default
$> echolor red "ERROR"
ERROR # In red tho
$> echolor red ERROR: An error message
ERROR: An error message # In red tho
$> echolor -n red "ERROR"
ERROR$> echo green "END"
END # In green tho