# Requirements files

The older method of defining requirements is still available, and is present in the majority of Skills available in the Marketplace. This uses a `requirements.txt` and/or `requirements.sh` file.

## requirements.txt

The `requirements.txt` file can only be used to define Python package dependencies. It uses the [standard Python PIP format](https://pip.readthedocs.io/en/1.1/requirements.html) to list Python packages from [PyPI](https://pypi.org/) to install. Each line in the file represents a separate package to install and must match the title provided by PyPI.

The following example will install the latest available versions of the [`requests`](https://pypi.org/project/requests/) and [`gensim`](https://pypi.org/project/gensim/) packages.

```
requests
gensim
```

If specific versions of a package are required, we can use comparison operators to indicate which version.

* `requests==2.22.0` The package must must be version `2.22.0`.
* `requests>=2.22.0` The package must be version `2.22.0` or higher.
* `requests<=2.22.0` The package must be version `2.22.0` or lower.

It is strongly recommended to only use these operators when required. If submitting a Skill to the Marketplace, you will be asked to provide reasoning as to why a specific version of a package is necessary.

### Examples of requirements.txt

* [Weather Skill](https://github.com/MycroftAI/skill-weather/blob/19.08/requirements.txt)
* [Wiki Skill](https://github.com/MycroftAI/skill-wiki/blob/19.08/requirements.txt)

## requirements.sh

The `requirements.sh` file may contain a shell script that is run during installation of the Skill. Shell scripting is beyond the scope of these documents, however there are many tutorials available online.

Prior to the `manifest.yml` file, this was the only method available to install system packages. If you are only installing packages, using the [`manifest.yml`](/docs/skill-development/skill-structure/dependencies/manifest-yml.md) file instead is recommended.

The contents of this file will be checked carefully if a Skill is submitted for inclusion in the [Skills Marketplace](https://market.mycroft.ai)

### Examples of requirements.sh

* [Zork (adventure game)](https://github.com/forslund/white-house-adventure/blob/6eba5df187bc8a7735b05e93a28a6390b8c6f40c/requirements.sh)


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