A mature bash file starter

starter.sh

#!/bin/bash

# allow color coding the console output.
# simple, but effective way to getting visual oomph to the screen

red='\033[0;31m'
green='\033[0;32m'
yellow='\033[0;33m'
white='\033[0;37m'
end_color='\033[0;37m'
base_color=$white
NC='\033[0m' # No Color

# force all normal output white!
echo -e "$base_color "

# the help function
function show_help {
cat << EOF

Usage: ${0##*/} [-hvd] [PARAM]
Some help description...
   PARAM a parameter passed to the script
   -h  this help.
   -v  verbose mode
   -d  debug mode

EOF
}

__error_exit=false
function _trap_finish {
    local linenum="$1"
    if [ $__error_exit = "false" ]; then
        echo -e "$green $(basename $0): Success! $end_color"
        echo ""
    fi
}

function _trap_error {
    __error_exit=true
    local linenum="$1"
    echo -e "$red ERROR $(basename $0):$linenum $end_color" 1>&2
    echo ""
    exit $? # actually exit the script. Especially if 'set -e' is not configured
}

function _trap_int {
    __error_exit=true
    local linenum="$1"
    echo ""
    echo -e "$yellow '$(basename $0)' was interrupted at $linenum $end_color" 1>&2
    echo ""
    exit $?
}

function error_exit {
    __error_exit=true
    local linenum="$1"
    echo ""
    echo -e "$red ERROR:$(basename $0):line #$1: $2 $end_color " 1>&2
    echo ""
    exit -1
}
trap '_trap_finish' EXIT
trap '_trap_error ${LINENO}' ERR
trap '_trap_int ${LINENO}' INT

set -e # exit on error
OPTIND=1 # Reset is necessary if getopts was used previously in the script.  It is a good idea to make this local in a function.
while getopts "hvd" opt; do
    case "$opt" in
        h)  show_help
            exit 0
            ;;
        v)  set -o;; # enable verbose mode
        d)  set -x;; # enable debug mode
        '?')
            show_help
            exit 0;;
    esac
done
shift "$((OPTIND-1))" # Shift the options and optional --.

param=${1}

if [[ -z $param ]]; then
    show_help
    error_exit $LINENO "$red PARAM not defined$white"
fi

echo "cmd 1"
echo "cmd 2"
echo "cmd 3"
sleep 20
#abra # some invalid command
echo "cmd n"