bash script for add/removing host in /etc/hosts

hosts.sh

#!/bin/bash

hosts() {
    VALID_COMMANDS=("help" "show" "samplefile" "activate" "deactivate")
    NO_ARG_COMMANDS=("help" "show" "samplefile")
    GREEN='\033[0;32m';
    RED='\033[0;31m';
    NOCOLOR='\033[0m';

read -r -d '' SAMPLE_ETC_HOSTS_FILE <<HEREDOC
#
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##

#%%%my-project.HOSTS%%%
127.0.0.1       foo.myproject.com

#%%%ALWAYS_ON%%%
127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost


# Added by Docker Desktop
# To allow the same kube context to work on the host and the container:
127.0.0.1 kubernetes.docker.internal
# End of section
HEREDOC


read -r -d '' HELP_MESSAGE <<HEREDOC
Usage:
    hosts help
    hosts show
    hosts samplefile
    hosts activate [SECTION]
    hosts deactivate [SECTION]
HEREDOC


    if [[ ! " ${VALID_COMMANDS[*]} " =~ " $1 " ]]
    then
        printf "${RED}Valid Commands are: ${VALID_COMMANDS[*]}${NOCOLOR}\n\n";
        return;
    fi    

    if [[ ! " ${NO_ARG_COMMANDS[*]} " =~ " $1 " && ! "$2" ]]
    then
        printf "${RED}You must provide the name of the section to activate/deactivate${NOCOLOR}\n\n";
        return;
    fi
   
    if [[ $1 == "help" ]]
    then
        echo "${HELP_MESSAGE}";
        return;
    elif [[ $1 == "show" ]]
    then
        printf "${GREEN}Contents of '/etc/hosts'${NOCOLOR}\n\n";
        sudo cat /etc/hosts;
        return;
    elif [[ $1 == "samplefile" ]]
    then
        echo "${SAMPLE_ETC_HOSTS_FILE}";
        return;
    elif [[ $1 == "activate" ]]
    then
        sudo sed -i'.original' -e '/#%%%'"${2}"'.HOSTS/,/#%%%/s/^#\([^%]\)/\1/g' /etc/hosts
        printf "${GREEN}Activated $2 section of /etc/hosts file${NOCOLOR}\n\n";
        return;
    elif [[ $1 == "deactivate" ]]
    then
        sudo sed -i'.original' -e '/#%%%'"${2}"'.HOSTS/,/#%%%/s/^\([^#]\)/#\1/g' /etc/hosts
        printf "${GREEN}Deactivated $2 section of /etc/hosts file${NOCOLOR}\n\n";
        return;
    fi
}

you can enable this function in your shell by running source ./hosts.sh