Bash script with flags example

#!/usr/bin/env bash

############################################
# Define variables
# Script Information
script="Hello World Example"
time="$(date)"                                                                                # The current time and date
TITLE="Hello World Example"                                                                   # This is the title of your
AUTHOR="textandmetal"                                                                         # Who wrote this script
TAGLINE="A super simple bash tool"                                                            # Tagline for your script in man page
manpagename=$(printf "$TITLE" | tr '[:lower:]' '[:upper:]')                                   # This transforms the $title variable to uppercase for man page

man_page(){
# This is the help page that is triggered by the -h flag
# Give the user important information and include common
# examples of usage

printf "
$manpagename(1)                      User Commands                      MANPAGE(1)

NAME
       $TITLE - $TAGLINE

SYNOPSIS
       $TITLE [OPTION]...
DESCRIPTION
       A simple bash script to demonstrate flags and some basic
       options for it.

       -h
              Show this man page

       -l
              View the licence for this script

       -d
              Debug your script, the script will start but has
              the -set x option enabled
"
}

view_licence(){
# The licence for this script, it takes the $AUTHOR and $TILE variable
printf "
$TITLE

 MIT License

 Copyright (c) 2019 $AUTHOR

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "'"Software"'"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "'"AS IS"'", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 "
}
txtred=$(tput setaf 1)
txtgrn=$(tput setaf 2)
txtylw=$(tput setaf 3)
txtblu=$(tput setaf 4)
txtpur=$(tput setaf 5)
txtcyn=$(tput setaf 6)
bold=$(tput bold)
txtrst=$(tput sgr0)

##############################################################################
############################### debug_program ################################
##############################################################################
# This launches the script in a simple debugging mode
debug_program(){
set -x
start_program
set +x
}
##############################################################################
##############################################################################

##############################################################################
############################### start_program ################################
##############################################################################
# This is the main part of the script that launches on execution without flags
start_program(){
echo "Hello World"
}
##############################################################################
##############################################################################

# getopts for options
while getopts dhl  option
do
case "${option}"
in
l) VIEWLICENCE="view_licence";;
h) MANPAGE="man_page";;
d) DEBUG="debug_program" ;;
esac
done

# Main Logic
while true
do
#clear
if [ $OPTIND -eq 1 ]; then start_program; fi
shift $((OPTIND-1))
#printf "$# non-option arguments"
$MANPAGE
$VIEWLICENCE
$DEBUG
exit
done