title: "Using multiple R versions on Linux"

author: "Alex M. Chubaty"

date: "29 Jun 2023"

output:

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highlight: pygments

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```{r setup, include=FALSE}

Unlike on Windows, most R users on linux tend to work with a single version of R -- whichever version is available in their software repositories.

With a little bit of work, it is possible to use multiple versions of R on Linux; however, you will need an account with `sudo` privileges to set this up.

The most common use case is to install R-devel alongside the current R version in order to facilitate package checking and testing prior to CRAN submission.

Additionally, you may wish to maintain older versions of R to maintain compatibility and reproducibility of old projects, scripts, etc.

This document provides an overview of several approaches to working with multiple versions of R on Linux - although these can also be used on macOS and Windows.

\newpage

This is the preferred solution, as it is self-contained.

Every time you start an instance of R in a Docker container, it starts in a "factory fresh" state, which means you will need to install additional packages into each new instance or save (commit) your changes for later reuse.

The advantages here are that packages installed for each project are kept separate, ensuring proper reproducibility and portability.

(Although [`renv`](https://rstudio.github.io/renv/) is also good for maintaining separate package libraries per project, it doesn't ensure system dependency separation.)

Please note that this guide is intended only to get you started with using R with Docker, not to be a full tutorial for more advanced Docker use.

See the official [Docker documentation](https://docs.docker.com/) and the [rocker project](https://github.com/rocker-org/rocker) for more advanced usage, including using containers with RStudio Server installed[^1] or using a virtual X server.

[^1]: <https://github.com/rocker-org/rocker-versioned2>

1. Install Docker following the instructions [here](https://docs.docker.com/engine/installation/).

2. Download the image for the version of R you wish to use:

```bash

docker pull r-base:3.6.3

```

3. Start a container running the R version of your choice:

```bash

\* NOTE: the `--rm` flag tells docker to remove the container after use.

If you wish to keep the container for reuse later (*e.g.*, so you don't need to reinstall packages, etc.), then omit this.

If you wish to keep the container for reuse later (*e.g.*, so you don't need to reinstall packages, etc.), then omit this.

Alternatively, there are docker images that include RStudio server built-in, so you can run a container and connect to it through your browser instead of having to work in a terminal.

1. *E.g.*, start a versioned container running RStudio that includes geospatial libraries from the unstable ubuntugis repo:

```bash

2. Look for the user password to appear (in red) once it's done setting up the container.

sudo sh -c "echo 'deb [arch=amd64] http://rig.r-pkg.org/deb rig main' > \