Elv

Introduction

elv is a command line interface program that lets you interact with Advent of Code API. Advent of Code is a yearly event that happens around the Christmas time. Eeach day of the event, one algorithmic riddle becomes available on its site and everyone can join by solving it and submitting their answers to it.

elv helps you interact with with Advent of Code via your terminal instead of the webpage. So far elv supports:

• downloading riddles' description
• downloading a riddle's input for a given year and day
• submitting answers to a riddle
• caching AoC responses whenever possible, so you minimize your footprint on AoC's servers

Installation

Using cargo

cargo is Rust's package manager. You can use it to install elv directly from crates.io. Once you install cargo, you can do it by running the below command in your terminal:

bash cargo install elv

After the installation, elv should be available from your CLI.

Downloading a binary

elv publishes a number of executables for different operating systems and architectures. Head to the releases subpage to check out the latest released version of elv.

Choose the binary matching your operating system and architecture

The archived binaries follow a simple naming scheme of: elv-{version}-{target-os-and-arch}.zip. Match your operating system with the file name and the architecture:

• Windows: look for one of the Windows binaries.
• Apple: if you use one of the Silicon processors, download the aarch64-apple-darwin target, otherwise download the other one.
• Linux: get one of the Linux distributions.

The choice between the GNU version and the other one depends on whether you have GNU installed. If yes, then go ahead and grab the appropriate GNU version.

Run the binary

The archives in each release contain a single executable file. Unpack the file. You need to put this executable file on your PATH, which translates to either unpacking the zip file to one of the directories already on PATH or unpacking anywhere you want and adding this location to PATH. If inspecting or changing your PATH is unclear, I recommend:

• Windows: https://www.h3xed.com/windows/how-to-add-to-and-edit-windows-path-variable
• Linux/MacOS: https://opensource.com/article/17/6/set-path-linux

After that, you should be able to call elv directly in your CLI:

bash elv

Installing from source

If you possess a Rust compiler and cargo, you can create your own executable from this repository. The steps are:

1. Clone the repository. You can use a terminal to clone the repository, e.g.: bash git clone git@github.com:kpagacz/elv.git # or https://github.com/kpagacz/elv.git
2. Install elv. Navigate towards the elv directory and run: bash cargo install --path .

Uninstallation

Examples

You need an Advent of Code session token to interact with its API. elv does not support authentication to the API on its own, so you need to get your token beforehand.

Getting the session token - IMPORTANT

You will need to log into Advent of Code. AoC site sends the session token back to you using cookies. You need to inspect the cookies and get the value of the one named session. This is your session token you can use with elv. The session token is valid for about a month, so remember to get another one, once the old one expires.

If you do not get the session token, you will not be able to interact with Advent of Code API using elv.

Downloading the description

Getting today's riddle description

This works only while the event is being held, not all the time of the year. While the event is not held, you need to specify the year and day of the challenge explicitly using -y and -d parameters.

bash elv -t <YOUR SESSION TOKEN> desc

Getting description of a particular riddle

You specify the day and the year of the riddle.

```bash elv -t -y 2021 -d 1 desc

Prints the description of the riddle published on the first of December 2021

```

Downloading the input

Getting today's riddle input

This works only while the event is being held, not all the time of the year. While the event is not held, you need to specify the year and day of the challenge explicitly using -y and -d parameters.

bash elv -t <YOUR SESSION TOKEN> input

Getting input for a particular riddle

You specify the day and the year of the riddle.

```bash elv -t -y 2021 -d 1 input

downloads the input for the riddle published on the 1st of December 2021

```

FAQ

How can I store the session token?

elv looks for your token in three places, starting from the first on the below list and moving to the next one in case it did not found the token already.

1. Passed as an argument to elv with the -t parameter:

```bash elv -t input

or

elv --token input ```

As a live example:

bash elv -t 01234567890123456789abcdefghi input

1. As an environment variable. elv looks for an environmental variable AOC_TOKEN while searching for your session token. Example:

bash export AOC_TOKEN=0123456789abcdefghi elv input

Despite the fact we have not provided the value for the --token parameter, elv will pick the value of AOC_TOKEN and use it as a token.

1. In a configuration file. elv creates a configuration file in your home directory.

How can I get the value of the session token?

The session token is sent to your http client (usually your browser) as a cookie, when you log into the Advent of Code web page. The easiest way to get the value of a cookie is using your browser's built-in inspection tools. Look for a way to inspect the cookies specific to your browser.