Pipable command to print in color?

Question

I'm a bit new to bash scripting, and I'm wondering if there is a program or built-in command to pipe to that will print in a specified color? Or is there an echo argument to do so?

Like I could do:

echo Hi | commandhere -arguement blue

and it would print "Hi" in the color blue?

Answer 1

I don't know of any utility for colored printing itself, but you can do it easily with a shell function like this:

# colorize stdin according to parameter passed (GREEN, CYAN, BLUE, YELLOW)
colorize(){
    GREEN="\033[0;32m"
    CYAN="\033[0;36m"
    GRAY="\033[0;37m"
    BLUE="\033[0;34m"
    YELLOW="\033[0;33m"
    NORMAL="\033[m"
    color=\$${1:-NORMAL}
    # activate color passed as argument
    echo -ne "`eval echo ${color}`"
    # read stdin (pipe) and print from it:
    cat
    # Note: if instead of reading from the pipe, you wanted to print
    # the additional parameters of the function, you could do:
    # shift; echo $*
    # back to normal (no color)
    echo -ne "${NORMAL}"
}
echo hi | colorize GREEN

If you want to check other colors, take a look at this list. You can add support for any color from there, simply creating an additional variable at this function with the correct name and value.