shell scripting topic

[hiulit]

@meleu Yeah! I know! I should've created a new branch for this new feature.. :P But It is safe to use master because I made the code backwards compatible, so nothing that was already there is broken and the new things aren't even documented yet. When using git for yourself (at least for me) you tend to use bad practices because it's easier, hehe!

A part from that, I see you point of just using height to maintain the aspect ratio, but I don't know how can I can create images for different resolutions that will look good on every device. I mean, if I use, let's say, the 576px you said, it will look too small on a 1920x1080 screen, I think. I'll give it a try anyway to see how "bad" (or good!) it looks. Thanks, as always! ;)

[meleu]

@hiulit said in shell scripting topic:

I don't know how can I can create images for different resolutions that will look good on every device. I mean, if I use, let's say, the 576px you said, it will look too small on a 1920x1080 screen, I think

My tool generate launching images with 576 pixels height and keep the aspect ratio of the image being used as background, Rokkervik's pixel-themed launching images are 480x272. All of them looks just fine on my 1920x1080 TVs...

If you create launching images 1920x1080 the resulting file can be very big and the raspberry pi can delay to display a big image

[hiulit]

@meleu Yeah, you're right. Pixel theme images look fine on my 1920x1080 monitor. I'll try it! ;)

[hiulit]

I've created this little script to format all theme.xml from a given EmulationStation theme with 4 spaces. It's really unnecessary, but I'm that kind of person :P

Here it goes:

#!/usr/bin/env bash

THEME="pixel"

for folder in "/etc/emulationstation/themes/$THEME/"*; do
    if [[ -d "$folder" ]]; then
        if [[ -f "$folder/theme.xml" ]]; then
            cp "$folder/theme.xml" "$folder/theme-backup.xml"
            xmlstarlet fo -s 4 "$folder/theme.xml" > "$folder/theme-indent.xml"
            sed -i '/\?xml/d' "$folder/theme-indent.xml"
            cp "$folder/theme-indent.xml" "$folder/theme.xml"
            rm "$folder/theme-indent.xml" "$folder/theme-backup.xml"
        fi
    fi
done

[hiulit]

When you have a dialog inside a dialog inside a dialog (and so on...), can the "Cancel" button act as a "Back" button? I know the label can be changed, but when you click it it goes back to the first dialog :(

[meleu]

@hiulit there's no "dialog inside a dialog". You execute a dialog and when you choose the "OK" or "Cancel" button the dialog finishes.

What causes that impression of a "dialog inside a dialog" is usually a dialog being called one right after another, each one inside its own while loop structure.

The example I have to show is one of my codes that I am least proud of when it comes to well-written code, but well, let's try...

Check the rpie-art code here: https://github.com/meleu/rpie-art/blob/master/rpie-art.sh

This while loop in main_menu() contains the first dialog. Depending on the option, the script calls another function which has another dialog. Let's follow the uninstall_art_menu() flow.

When the user choose X on the main_menu(), the script calls the uninstall_art_menu() function which has another dialog where you can:

1. Choose Cancel: the logic flow returns to main_menu() and that loop calls the main_menu()'s dialog again.
2. Choose a valid option. Which calls another function which has another dialog and the chain-of-dialogs goes on...

Eh... I'm not sure if I explained well. 😅

Read, check the code and reread. If you still don't understand feel free to ask. ;-)

[hiulit]

@meleu Thanks! That's what I thought. I'll create some functions then, as you did ;)

[hiulit]

Hi there!
Can somebody help me figure this out?

I have an argument passed to a shell script fun-facts-splashscreens.sh --create-fun-fact that can have:

• no options
• 1 option [system]
• 2 options [system rom]

How can I write a help message? --create -fun-fact [] [system] [system rom]?

Thanks!

[mitu]

@hiulit Add a -h option and display the help when this option is passed to the script.

[hiulit]

@mitu I'm sorry, I didn't explain myself clearly enough.

I already have a -h option that shows all the options available. What I meant is, how should I tell the user that the option --create-fun-fact can have:

• no options
• 1 option [system]
• 2 options [system rom]

That's what I've come up with: --create-fun-fact [] [system] [system rom]
Is that correct?

Did I explain myself better this time? :P

[mitu]

@hiulit said in shell scripting topic:

--create-fun-fact [] [system] [system rom]

Ah, ok. I think the correct syntax would be

--create-fun-fact [SYSTEM] [ROM]

Usually an argument in brackets ([arg]) means the argument is optional.

[hiulit]

@mitu I see! And if an argument is NOT optional? I have some of those around :P

[mitu]

@hiulit If it's not optional, just remove the brackets.

--create-fun-fact system [rom]

[meleu]

@hiulit can you explain the use case and provide some examples?

I'm sure we can find ways to make an option have zero, one or two options, but from a user point of view I think it's a bit confusing.

EDIT:
I can't see what would be the use for --create-fun-fact system rom, but if it's intended to be used on RetroPie, you can detect the system by looking the directory where the rom is located.

[hiulit]

@meleu I'll try to explain myself even better than the last time :P Here we go!

This all comes from the fun-facts-splashscreens-runcommand-onend.sh that has these lines:

SYSTEM="$1"
ROM_PATH="$3"
sudo "$SCRIPT_DIR/fun-facts-splashscreens.sh" --create-fun-fact "$SYSTEM" "ROM_PATH"

This is what creates the launching images when stoping the game. This is something the user doesn't need to care about. But then I already had --create-fun-fact in the help message so I wanted to let the user use it, like this:

• --create-fun-fact with no options passed creates a boot splashscreen.
• --create-fun-fact [SYSTEM] (SYSTEM can be all or any RetroPie system) creates launching images for all the systems, or the given system with the system's logo (and console if it exists).
• --create-fun-fact [SYSTEM] [ROM] (ROM can be an absolute path or just the ROM's name + ext, and then it takes the given system to look for the path) creates a launching image for the game.

Examples:

• --create-fun-fact
• --create-fun-fact all
• --create-fun-fact megadrive
• --create-fun-fact megadrive "/home/RetroPie/megadrive/Sonic the Hedgehog.zip"
• --create-fun-fact megadrive "Sonic the Hedgehog.zip"

I can see that from the user's perspective it could be a little confusing... Maybe it's better to split --create-fun-fact into two separate functions --create-fun-fact-boot-splashscreen and --create-fun-fact-launching-images.

Maybe I should remove this option from the help message? Just have it for myself to test?
That's something that can be done via the GUI, btw:

[meleu]

@hiulit You wouldn't want to create a launching image for Sonic using a NES splashscreen, would you? Well, my suggestion below does not have this kind of flexibility, but here it go:

help message

--create-fun-fact [system|path/to/a/ROM]     no arguments = create boot splashscreen
                                             system = create a launching image for system
                                             ROM = create a launching image for a ROM

If you wanna use this approach, please write a better help message for this option! ;)

code

#!/bin/bash

user="$SUDO_USER"
[[ -z "$user" ]] && user="$(id -un)"
home="$(eval echo ~$user)"

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

function get_options() {

    case "$1" in

#H --create-fun-fact [system|path/to/a/ROM]     no arguments = create boot splashscreen
#H                                              system = create a launching image for system
#H                                              ROM = create a launching image for a ROM
        --create-fun-fact)
            if [[ -z "$2" ]]; then
                # NOTE: for this usecase the --create-fun-fact MUST be the
                #       last parameter used in the command line.
                echo "Let's create a boot splashscreen with a fun fact!"

            elif [[ -f "$2" ]]; then
                # NOTE: if it's a regular file, let's check if it's a ROM and
                #       create a splashscreen for this game.
                local rom_full_path="$(realpath "$2")"

                if [[ "$rom_full_path" != "$RP_ROMS_DIR"* ]]; then
                    echo "ERROR: \"$2\" is not on a valid ROM directory" >&2
                    exit 1
                fi

                # Reference for the tricks used to get the system's name below:
                # http://www.tldp.org/LDP/abs/html/parameter-substitution.html#PSOREX2
                system="${rom_full_path#$RP_ROMS_DIR/}"
                system="${system%/*}"

                echo "Let's create a launching image for \"$2\" using the ${system}'s one!"

            elif [[ -d "$RP_CONFIG_DIR/$2" ]]; then
                echo "Let's create a launching image for \"$2\" system!"

            else
                echo "ERROR: \"$2\": invalid argument." >&2
                exit 1
            fi
            ;;

#H --help                                       Print the help message and exit.
        --help|-h)
            sed '/^#H /!d; s/^#H //' "$0"
            echo
            exit 0
            ;;
    esac
}

get_options "$@"

testing

$ ./cff.sh --create-fun-fact
Let's create a boot splashscreen with a fun fact!

$ ./cff.sh --create-fun-fact abcd
ERROR: "abcd": invalid argument.

$ ./cff.sh --create-fun-fact nes
Let's create a launching image for "nes" system!

$ ./cff.sh --create-fun-fact ~/RetroPie/roms/nes
ERROR: "/home/meleu/RetroPie/roms/nes": invalid argument.

$ ./cff.sh --create-fun-fact ~/RetroPie/roms/nes/Contra\ \(USA\).zip 
Let's create a launching image for "/home/meleu/RetroPie/roms/nes/Contra (USA).zip" using the nes's one!

[hiulit]

@meleu Thanks for your reply! And no, I wouldn't want that

launching image for Sonic using a NES splashscreen
But my script prevents from doing that.

I'll try to paste every piece of code that I have, because it's very similar to what you have:

-cff|--create-fun-fact)
    is_fun_facts_empty
    if [[ -z "$2" ]]; then
        create_fun_fact
    else
        shift
        create_fun_fact "$@"
        shift
    fi
    ;;

If no arguments are passed called create_fun_fact without arguments, if there are any arguments, pass them all.

function create_fun_fact() {
    if [[ -z "$1" ]]; then
        create_fun_fact_boot
    else
        create_fun_fact_launching "$@"
    fi
}

There's more things going one here, but it basically calls one function or another depending on if there are arguments.
create_fun_fact_boot is self explanatory.
create_funfact_launching takes all the arguments and then:

function create_fun_fact_launching() {
    local system="$1"
    local rom_path="$2"

    if [[ "$system" == "all" ]]; then
        // Loop all systems and call create_fun_fact_launching "$system"
    else
        if [[ -n "$rom_path" ]]; then
            // Check if $system it's the same in "rom_path"
            if true
                // Create launching image for the game
            else
                // Create launching image for the system
        else
            // Create launching image for the system
        fi
    fi
}

More or less that what I do. I think it's similar of what you wrote.

But then again, I think maybe it's better to to have 2 separate options:

• --create-fun-facts-boot-splashscreen(doesn't accept any argument)
• --create-fun-facts-launching-images (accepts system and rom)

EDIT:
You can take a look for youself https://github.com/hiulit/RetroPie-Fun-Facts-Splashscreens/blob/new-gui-menu/fun-facts-splashscreens.sh ;)

[meleu]

I've just found this and decided to share here:

Pure Bash Bible

The goal of this book is to document known and unknown methods of doing various tasks using only built-in bash features. Using the snippets from this bible can help remove unneeded dependencies from scripts and in most cases make them faster.

[cyperghost]

@meleu Wow this is really helpfull ;) Cool snippets for bash coders. Thank you so much.

For ex:
Reverse array I did

for ((z=${#array[*]}-1; z>-1; z--)); do
       echo "${array[z]}"
done

Reverse array with the bash-bible

## Reverse an array

# ```sh
reverse_array() {
    # Usage: reverse_array "array"
    shopt -s extdebug
    f()(printf '%s\n' "${BASH_ARGV[@]}"); f "$@"
    shopt -u extdebug
}
# ```

Up to now my version seems a bit less complex. Maybe it's due my limited coding skills. I'm still learning ....

[cyperghost]

@meleu I think that's just a note to me ... BashPitfalls

function1(){
    local status=$(false)
    echo $?
}

Will return 0 which is obviously wrong
So the return code 0 just indicates the correct setting of a local setted value, which was correctly done ;)

So to get out of this make following

function1(){
    local status
    status=$(false)
    echo $?
}

This will put out correct value for "error" 1