[SCRIPT] RetroPie Shell Script Boilerplate

[hiulit]

I'm starting to like creating scripts for RetroPie so I created a RetroPie Shell Script Boilerplate for myself and now I'd like to present it to you and get some feedback.

Basically, it's a starting point with:

• Some variables and functions that I found myself using in every script I created.
• A config file, because I use it quite often.
• It also includes a README.md and a CHANGELOG.md to document the script.
• Some stuff for GitHub: a LICENSE and a CONTRIBUTING.md.

There a lot of comments and examples on how to use the functions and how to write the documentation.
Everything that's encapsulated in [] is editable and the comments that should be removed when the script is in 'production' are marked.

UPDATE 1:

• Merged #2 from @meleu .
• Added check_dependencies().
• Added reset_config() to use it in conjunction with set_config() and get_config().
• Added --version (because I think everyone should use it :P)
• Added 2 ways to find /home.
• Added more useful global variables.

Well, here it is:

#!/usr/bin/env bash
# [SCRIPT_NAME] (e.g.: script_template.sh)
#
# [SCRIPT_TITLE] (e.g.: RetroPie Shell Script Boilerplate)
# [SCRIPT_DESCRIPTION] (e.g. A template for building shell scripts for RetroPie.)
#
# Author: [AUTHOR] (e.g. hiulit)
# Repository: [REPO_URL] (e.g. https://github.com/hiulit/RetroPie-Shell-Script-Boilerplate)
# License: [LICENSE] [LICENSE_URL] (e.g. MIT https://github.com/hiulit/RetroPie-Shell-Script-Boilerplate/blob/master/LICENSE)
#
# Requirements:
# - RetroPie x.x.x (e.g. RetroPie 4.x.x)
# - [PACKAGE_NAME] (e.g. libav-tools)

# Globals ####################################################################

# If the script is called via sudo, detect the user who called it and the homedir.
user="$SUDO_USER"
[[ -z "$user" ]] && user="$(id -un)"

home="$(eval echo ~$user)"
# If you really need that the script is run by root user (e.g. script called
# from '/etc/rc.local') the approach below can work better to get the homedir
# of the RetroPie user.
# Comment the code above and uncomment the code below.
#home="$(find /home -type d -name RetroPie -print -quit 2>/dev/null)"
#home="${home%/RetroPie}"

readonly RP_DIR="$home/RetroPie"
readonly RP_CONFIG_DIR="/opt/retropie/configs"

readonly SCRIPT_VERSION="0.0.0" # Use Semantinc Versioning https://semver.org/
readonly SCRIPT_DIR="$(cd "$(dirname $0)" && pwd)"
readonly SCRIPT_NAME="$(basename "$0")"
readonly SCRIPT_FULL="$SCRIPT_DIR/$SCRIPT_NAME"
#readonly SCRIPT_CFG="$SCRIPT_DIR/[CONFIG_FILE]" # Uncomment if you want/need to use a config file.
readonly SCRIPT_TITLE="[SCRIPT_TITLE]"
readonly SCRIPT_DESCRIPTION="[SCRIPT_DESCRIPTION]"
#readonly SCRIPTMODULE_DIR="/opt/retropie/supplementary/[SCRIPTMODULE_NAME]" # Uncomment if you want/need to use a scriptmoodule.

# Other variables that can be useful.
#readonly DEPENDENCIES=("[PACKAGE_1]" "[PACKAGE_2]" "[PACKAGE_N]")
#readonly ROMS_DIR="$RP_DIR/roms"
#readonly ES_THEMES_DIR="/etc/emulationstation/themes"
#readonly RCLOCAL="/etc/rc.local"
#readonly GIT_REPO_URL="[REPO_URL]"
#readonly GIT_SCRIPT_URL="[REPO_URL]/[path/to/script].sh


# Variables ##################################################################

# Add your own variables here.


# Functions ##################################################################

function is_retropie() {
    [[ -d "$RP_DIR" && -d "$home/.emulationstation" && -d "/opt/retropie" ]]
}


function is_sudo() {
    [[ "$(id -u)" -eq 0 ]]
}


# If your script has dependencies, just use the DEPENDENCIES variable on the definitions above.
# Otherwise, leave it as is.
function check_dependencies() {
    local pkg
    for pkg in "${DEPENDENCIES[@]}";do
        if ! dpkg-query -W -f='${Status}' "$pkg" | grep -qwo "installed"; then
            echo "ERROR: The '$pkg' package is not installed!" >&2
            echo "Would you like to install it now?"
            local options=("Yes" "No")
            local option
            select option in "${options[@]}"; do
                case "$option" in
                    Yes)
                        if ! which apt-get > /dev/null; then
                            echo "ERROR: Can't install '$pkg' automatically. Try to install it manually." >&2
                            exit 1
                        else
                            sudo apt-get install "$pkg"
                            break
                        fi
                        ;;
                    No)
                        echo "ERROR: Can't launch the script if the '$pkg' package is not installed." >&2
                        exit 1
                        ;;
                    *)
                        echo "Invalid option. Choose a number between 1 and ${#options[@]}."
                        ;;
                esac
            done
        fi
    done
}


function check_argument() {
    # This method doesn't accept arguments starting with '-'.
    if [[ -z "$2" || "$2" =~ ^- ]]; then
        echo >&2
        echo "ERROR: '$1' is missing an argument." >&2
        echo >&2
        echo "Try '$0 --help' for more info." >&2
        echo >&2
        return 1
    fi
}


# If you are using the config file, uncomment set_config() and get_config().
# In addition, you can also uncomment reset_config() if you need it.
# USAGE:
# set_config "[KEY]" "[VALUE]" - Sets the VALUE to the KEY in $SCRIPT_CFG.
# get_config "[KEY]" - Returns the KEY's VALUE in $SCRIPT_CFG.
# reset_config - Resets all VALUES in $SCRIPT_CFG.
#
# function set_config() {
#     sed -i "s|^\($1\s*=\s*\).*|\1\"$2\"|" "$SCRIPT_CFG"
#     echo "\"$1\" set to \"$2\"."
# }
#
#
# function get_config() {
#     local config
#     config="$(grep -Po "(?<=^$1 = ).*" "$SCRIPT_CFG")"
#     config="${config%\"}"
#     config="${config#\"}"
#     echo "$config"
# }
#
#
# function reset_config() {
#     while read line; do
#         set_config "$line" ""
#     done < <(grep -Po ".*?(?=\ = )" "$SCRIPT_CFG")
# }


function usage() {
    echo
    echo "USAGE: $0 [OPTIONS]" # Add 'sudo' before '$0' if the script needs to be run under sudo (e.g. USAGE: sudo $0 [OPTIONS]). Don't change [OPTIONS]! Remember to remove this comment.
    echo
    echo "Use '$0 --help' to see all the options." # Add 'sudo' before '$0' if the script needs to be run under sudo (e.g. Use 'sudo $0 --help' ...). Remember to remove this comment.
}

# Add your own functions here.

# You can add as many options as you want.
# To add a new option -> Copy and paste from '#H -[O], --[OPTION] ...' until ';;' and make the desired changes.
# If you want to align the descriptions of the options, just play with adding/removing spaces/tabs :P
function get_options() {
    if [[ -z "$1" ]]; then
        usage
        exit 0
    else
        case "$1" in
#H -h, --help                   Print the help message and exit.
            -h|--help)
                echo
                echo "$SCRIPT_TITLE"
                for ((i=1; i<="${#SCRIPT_TITLE}"; i+=1)); do [[ -n "$dashes" ]] && dashes+="-" || dashes="-"; done && echo "$dashes"
                echo "$SCRIPT_DESCRIPTION"
                echo
                echo "USAGE: $0 [OPTIONS]" # Add 'sudo' before '$0' if the script needs to be run under sudo (e.g. USAGE: sudo $0 [OPTIONS]). Don't change [OPTIONS]! Remember to remove this comment.
                echo
                echo "OPTIONS:"
                echo
                sed '/^#H /!d; s/^#H //' "$0"
                echo
                exit 0
                ;;
#H -v, --version                Show script version.
            -v|--version)
                echo "$SCRIPT_VERSION"
                ;;
#H -[O], --[OPTION] (e.g '-v, --version')       [OPTION_DESCRIPTION] (e.g. Show script version.).
            -[O]|--[OPTION])
                # If the option has arguments, uncomment the code below.
                # check_argument "$1" "$2" || exit 1
                # shift

                # Add the functions for this options here.
                ;;
            *)
                echo "ERROR: invalid option '$1'" >&2
                exit 2
                ;;
        esac
    fi
}

function main() {
    # If you need to check if sudo is used, uncomment the code below.
    # Remember to add 'sudo' in 'usage' and 'help'.
    # if ! is_sudo; then
    #     echo "ERROR: Script must be run under sudo."
    #     usage
    #     exit 1
    # fi

    if ! is_retropie; then
        echo "ERROR: RetroPie is not installed. Aborting ..." >&2
        exit 1
    fi

    check_dependencies

    get_options "$@"
}

main "$@"

and the config file:

# Settings for [SCRIPT_TITLE] (e.g. RetroPie Shell Script Boilerplate)

# Add your own [key = "value"] (e.g. path_to_whatever = "/path/to/whatever")
# [KEY] WITHOUT quotes.
# [VALUE] WITH quotes.
# There MUST be 1 space before and after '='.
# To indicate that a [KEY] has NO [VALUE] or is NOT SET, just leave the quotes, like this: "".

# Description of the [key = "value"] (e.g. # Set path to whatever).
[KEY] = "[VALUE]"

# Add your own [key = "value"]

I would like to especially thank @meleu for helping me with other projects I've worked on.

I hope that somebody will find this useful and also I'd like to hear some feedback (criticism, suggestions, etc.) so I can improve it and in addition improve my skills developing scripts for RetroPie :D

[cyperghost]

@hiulit If I ever will use config files than this would be a good starting point ;) Usually I parse arguments via command parameters as all of my scripts are very tight and need no configuration.

[meleu]

@hiulit OMFG! I was thinking about making the same thing but was a bit unmotivated to start it from scratch. Now you started it... such a relief! :D

After writing all those scripts here and there for the RetroPie community I think I have something to share. I hope to find some time to contribute on your repo.

Thanks for bringing this up!

[hiulit]

@cyperghost I'm glad you like! :D
I like to use config files because it makes the script more 'user-friendly' in my opinion. Feel free to contribute to the repo if you find a better way of handling config files (setting and getting values)

[hiulit]

@meleu Awesome! I'm already waiting for your contributions! And any other person who'd like to contribute too.
Together we can come up with a nice and useful boilerplate :)

[meleu]

@hiulit I think the comments are kinda wordy. Would you mind if I change the style, trying to reduce the text a bit?

[hiulit]

@meleu Yeah, sure, no problem! Go for it!

[meleu]

@hiulit PR submitted.

[hiulit]

@meleu Thanks! PR commented ;)

[hiulit]

I've updated the RetroPie Shell Script Boilerplate:

UPDATE 1:

• Merged #2 from @meleu .
• Added check_dependencies().
• Added reset_config() to use it in conjunction with set_config() and get_config().
• Added --version (because I think everyone should use it :P)
• Added 2 ways to find /home.
• Added more useful global variables.

These changes are also reflected in the first comment.

Coming soon... dialog functions!! Again, thanks to @meleu ;)

[cyperghost]

@hiulit Some additional functions

# This will determine of savestate directory = config
# This is part of hiuilits Boilerplate script, with small modification
# if '~' is detected then expand full homepath
function get_config() {
    local config
    config="$(grep -Po "(?<=^$1 = ).*" "$CONFIG_FILE")"
    config="${config%\"}"
    config="${config#\"}"
    # [[ ${config:0:1} = "~" ]] && config="${config#??}" && config=~/"$config" # Expand homepath
    # [[ -z ${config##*/} ]] && config="${config%?}" # Sanitize pathes if last character is a /
    # [[ ${config:0:1} != "/" ]] && config="annother value because it is likely no path"
    echo "$config"
}

# This will determine which script is curently running
# Is it 'runcommand-onend.sh' or 'runcommand-onstart.sh'
# It will extract 'end' or 'start' ... Usefull if you need to know which runcommand called the script
function get_runcommand() {
   local i
   local file_array=("runcommand-onend.sh" "runcommand-onstart.sh")
   for i in "${file_array[@]}"
   do
      [[ $(pgrep -f "$i") ]] && i="${i#*-on}" && echo "${i%.*}"
   done
}

# Determining file ages
function file_age() {
    echo "$(date +%s -r "$1")"
}

[hiulit]

@cyperghost Hey, thanks! I'll take a look at them ;)