bash_script_template

#!/usr/bin/env bash

normal=$(tput sgr0)
bold=$(tput bold)
red=$(tput setaf 1)
green=$(tput setaf 2)
yellow=$(tput setaf 3)
blue=$(tput setaf 4)
magenta=$(tput setaf 5)
cyan=$(tput setaf 6)

# Usage: info "message"
# Example: info "It's Working"
# Output (to STDOUT): [...] It's Working
info ()
{
    printf "%b" "[${green}...${normal}] $1\n"
}

# Usage: prompt "question"
# Example: prompt "What's Your Name?"
# Output (to STDOUT): [ ? ] What's Your Name?  
prompt ()
{
    printf "%b" "[${yellow} ? ${normal}] $1 "
}

# Usage: error ["message"]
# Example: error "You're Ugly"
# Output (to STDERR): [ERROR] /script/name: You're Ugly
error ()
{
    printf "%b" "[${red}ERROR${normal}] ${0}: ${1:-'Unkown Error'}\n" >&2
}

# Usage: fail "message" [exit_code]
# Example: fail "Unknown Option" 254
fail ()
{
    error "$1"

    case $2 in
        ''|*[!0-9]*)
            exit_code=1
            ;;
        *)
            exit_code=$2
        ;;
    esac

    exit $exit_code
}

# ask function https://gist.github.com/davejamesmiller/1965569
# Usage: ask "Yes or No?" [default option]
# Example: if "Yes or No?" Y; then
ask ()
{
    while true; do
 
        if [ "${2:-}" = "Y" ]; then
            prompt_tail="Y/n"
            default=Y
        elif [ "${2:-}" = "N" ]; then
            prompt_tail="y/N"
            default=N
        else
            prompt_tail="y/n"
            default=
        fi
 
        # Ask the question
        prompt "$1 [$prompt_tail]"
        read REPLY
 
        # Default?
        if [ -z "$REPLY" ]; then
            REPLY=$default
        fi
 
        # Check if the reply is valid
        case "$REPLY" in
            Y*|y*) return 0 ;;
            N*|n*) return 1 ;;
        esac

    done
}

# Usage: show_help [exit_code]
# Example: show_help 254
show_help ()
{
    cat <<HELP
    Usage:
        $0 [OPTION]...

    OPTIONS:
        --help, -h:    Show this help and exit

    Example:
        $0 **example**

HELP

    # Fail with general error if status code passed
    case $1 in
        ''|*[!0-9]*)
            exit_code=1
            ;;
        *)
            exit_code=$1
        ;;
    esac

    exit $exit_code
}

argument_expected()
{
    fail "$1 expected an argument"
}

finally()
{
    if [ ! -z $example_one ]; then
        info "Finally, Example One: \"$example_one\""
    fi

    if [ ! -z $example_two ]; then
        info "Finally, Example Two: \"$example_two\""
    fi

}

check_args()
{
    while [ ! -z "$1" ]; do
        local arg="$1"
        case "$1" in
            -h|--help) 
                local help=0
                shift
                ;; 
            -ex1|--example-one)
                shift

                if [ -z $1 ] || [[ "$1" == -* ]]; then
                    argument_expected $arg
                fi

                example_one=$1
                shift
                ;;
            -ex2|--example-two)
                # Simple boolean flag–call function here
                example_two="Two"
                shift
                ;;
            *)
                fail "Unknown option $1"
                shift
                ;;
        esac
    done

    if [ ! -z $help ]; then
        show_help $help
    fi

    finally

    exit 0
}

main()
{
    if [ -z $1 ]; then
        show_help
    fi

    check_args "$@"
}

main "$@"