A bash function to echo coloured log messages.

print_with_colour.sh

#!/usr/bin/env bash

# Function echo text to the screen.
# There are two ways to invoke this:
#
#  print LEVEL MESSAGE
#  print MESSAGE
#
# In the first case, LEVEL can be one of: DEBUG, INFO, SUCCESS, WARNING, or ERROR.
# This determines the colour used to display the message. If the level is not recognised then it defaults to INFO.
# In the second case, the message is displayed as though LEVEL was set to INFO.
function print
{
    # If there are two arguments then the first is LEVEL and the second is MESSAGE.
    # If there is only one argument then it is the message. LEVEL defaults to INFO.
    local level="${1:-}"
    local message="${2:-}"
    if [[ "${message}" = "" ]]; then
        message="${1:-}"
        level="INFO"
    fi

    local format="\e[0m"
    local resetFormat="\e[0m"
    local prefix=""

    # Pick a suitable display colour.
    case "${level}" in
        "DEBUG" )
            # Dim text
            format="\e[2m"
            prefix="[ DEBUG ]: "
            ;;

        "INFO" )
            # Default text format.
            prefix="[ INFO  ]: "
            ;;

        "SUCCESS" )
            # Green text.
            format="\e[32m"
            prefix="[SUCCESS]: "
            ;;

        "WARNING" )
            # Yellow text.
            format="\e[33m"
            prefix="[WARNING]: "
            ;;

        "ERROR" )
            # Bold/bright red text.
            format="\e[1;31m"
            prefix="[ ERROR ]: "
            ;;

        * )
            # Use default format.
            prefix="[${level}]: "
            ;;
    esac

    echo -e "${resetFormat}${format}${prefix}${message}${resetFormat}"
}

Example usage:

print DEBUG "This is a debugging message."
print INFO "This message provides general status information."
print SUCCESS "This message indicates that something has succeeded."
print WARNING "Something concerning has happened."
print ERROR "Something really bad has happened."

print "Messages default to INFO if no level is provided."
print CUSTOM_LEVEL "This message has a custom level tag. It uses INFO formatting though."