Simple R Version Management: renv

renv lets you easily switch between multiple versions of R. It's simple, unobtrusive, and follows the UNIX tradition of single-purpose tools that do one thing well.

This project was forked from pyenv, and modified for R.

renv does...

Let you change the global R version on a per-user basis.
Provide support for per-project R versions.
Allow you to override the R version with an environment variable.
Search commands from multiple versions of R at a time.

renv does not...

Depend on R itself. renv was made from pure shell scripts. There is no bootstrap problem of R.
Need to be loaded into your shell. Instead, renv's shim approach works by adding a directory to your $PATH.
Manage virtualenv. Of course, you can create virtualenv yourself.

Common usage

Install a new R version

From a bash terminal:

# Check available versions to install
$ renv install --list
# Install a new R version, 4.0.0 for example
$ renv install 4.0.0
# Set it as the local R version to use for the current directory (project)
$ renv local 4.0.0
# Start R, and surprise! it is version 4.0.0
$ R

Update RStudio's data to allow working with different R versions

From a bash terminal:

# Check currently installed versions
$ renv versions
# Update RStudio's data
$ renv update-rstudio-launcher
# And surprise again! Right click your RStudio launcher and start it running any other R version.

How It Works

At a high level, renv intercepts R commands using shim executables injected into your PATH, determines which R version has been specified by your application, and passes your commands along to the correct R installation.

Understanding PATH

When you run a command like R, your operating system searches through a list of directories to find an executable file with that name. This list of directories lives in an environment variable called PATH, with each directory in the list separated by a colon:

/usr/local/bin:/usr/bin:/bin

Directories in PATH are searched from left to right, so a matching executable in a directory at the beginning of the list takes precedence over another one at the end. In this example, the /usr/local/bin directory will be searched first, then /usr/bin, then /bin.

Understanding Shims

renv works by inserting a directory of shims at the front of your PATH:

$(renv root)/shims:/usr/local/bin:/usr/bin:/bin

Through a process called rehashing, renv maintains shims in that directory to match every R command across every installed version of R.

Shims are lightweight executables that simply pass your command along to renv. So with renv installed, when you run, say, R, your operating system will do the following:

Search your PATH for an executable file named R
Find the renv shim named R at the beginning of your PATH
Run the shim named R, which in turn passes the command along to renv

Choosing the R Version

When you execute a shim, renv determines which R version to use by reading it from the following sources, in this order:

The RENV_VERSION environment variable (if specified). You can use the renv shell command to set this environment variable in your current shell session.
The application-specific .R-version file in the current directory (if present). You can modify the current directory's .R-version file with the renv local command.
The first .R-version file found (if any) by searching each parent directory, until reaching the root of your filesystem.
The global $(renv root)/version file. You can modify this file using the renv global command. If the global version file is not present, renv assumes you want to use the "system" R. (In other words, whatever version would run if renv weren't in your PATH.)

Locating the R Installation

Once renv has determined which version of R your application has specified, it passes the command along to the corresponding R installation.

Each R version is installed into its own directory under $(renv root)/versions.

For example, you might have these versions installed:

$(renv root)/versions/3.0.0/
$(renv root)/versions/3.6.3/
$(renv root)/versions/4.0.0/

As far as renv is concerned, version names are simply the directories in $(renv root)/versions.

Installation

Basic GitHub Checkout

This will get you going with the latest version of renv and make it easy to fork and contribute any changes back upstream.

Check out renv where you want it installed. A good place to choose is $HOME/.renv (but you can install it somewhere else).
```
 $ git clone https://github.com/jcrodriguez1989/renv-installer.git ~/.renv
```

Define environment variable RENV_ROOT to point to the path where renv repo is cloned and add $RENV_ROOT/bin to your $PATH for access to the renv command-line utility.

For bash:

$ echo 'export RENV_ROOT="$HOME/.renv"' >> ~/.bash_profile
$ echo 'export PATH="$RENV_ROOT/bin:$PATH"' >> ~/.bash_profile

For Ubuntu Desktop:

$ echo 'export RENV_ROOT="$HOME/.renv"' >> ~/.bashrc
$ echo 'export PATH="$RENV_ROOT/bin:$PATH"' >> ~/.bashrc

For Zsh:

$ echo 'export RENV_ROOT="$HOME/.renv"' >> ~/.zshrc
$ echo 'export PATH="$RENV_ROOT/bin:$PATH"' >> ~/.zshrc

For Fish shell:

$ set -Ux RENV_ROOT $HOME/.renv
$ set -Ux fish_user_paths $RENV_ROOT/bin $fish_user_paths

Proxy note: If you use a proxy, export http_proxy and HTTPS_PROXY too.

Add renv init to your shell to enable shims and autocompletion. Please make sure eval "$(renv init -)" is placed toward the end of the shell configuration file since it manipulates PATH during the initialization.
```
$ echo -e 'if command -v renv 1>/dev/null 2>&1; then\n  eval "$(renv init -)"\nfi' >> ~/.bash_profile
```
- Zsh note: Modify your ~/.zshrc file instead of ~/.bash_profile.
- fish note: Use renv init - | source instead of eval (renv init -).
- Ubuntu and Fedora note: Modify your ~/.bashrc file instead of ~/.bash_profile.
General warning: There are some systems where the BASH_ENV variable is configured to point to .bashrc. On such systems you should almost certainly put the above mentioned line eval "$(renv init -)" into .bash_profile, and not into .bashrc. Otherwise you may observe strange behaviour, such as renv getting into an infinite loop. See #264 for details.
Restart your shell so the path changes take effect. You can now begin using renv.
```
$ exec "$SHELL"
```
Install R build dependencies before attempting to install a new R version. The renv wiki provides suggested installation packages and commands for various operating systems.
Install R versions into $(renv root)/versions. For example, to download and install R 3.0.0, run:
```
$ renv install 3.0.0
```
NOTE: If you need to pass configure option to build, please use CONFIGURE_OPTS environment variable.

NOTE: If you want to use proxy to download, please use http_proxy and https_proxy environment variable.

NOTE: If you are having trouble installing an R version, please visit the wiki page about Common Build Problems

Upgrading

If you've installed renv using the instructions above, you can upgrade your installation at any time using git.

To upgrade to the latest development version of renv, use git pull:

$ cd $(renv root)
$ git pull

Uninstalling renv

The simplicity of renv makes it easy to temporarily disable it, or uninstall from the system.

To disable renv managing your R versions, simply remove the renv init line from your shell startup configuration. This will remove renv shims directory from PATH, and future invocations like R will execute the system R version, as before renv.

renv will still be accessible on the command line, but your R apps won't be affected by version switching.

To completely uninstall renv, perform step (1) and then remove its root directory. This will delete all R versions that were installed under $(renv root)/versions/ directory:
```
rm -rf $(renv root)
```

Post-installation

Then follow the rest of the post-installation steps under Basic GitHub Checkout above, starting with #3 ("Add renv init to your shell to enable shims and autocompletion").

Advanced Configuration

Skip this section unless you must know what every line in your shell profile is doing.

renv init is the only command that crosses the line of loading extra commands into your shell. Coming from rvm, some of you might be opposed to this idea. Here's what renv init actually does:

Sets up your shims path. This is the only requirement for renv to function properly. You can do this by hand by prepending $(renv root)/shims to your $PATH.
Installs autocompletion. This is entirely optional but pretty useful. Sourcing $(renv root)/completions/renv.bash will set that up. There is also a $(renv root)/completions/renv.zsh for Zsh users.
Rehashes shims. From time to time you'll need to rebuild your shim files. Doing this on init makes sure everything is up to date. You can always run renv rehash manually.
Installs the sh dispatcher. This bit is also optional, but allows renv and plugins to change variables in your current shell, making commands like renv shell possible. The sh dispatcher doesn't do anything crazy like override cd or hack your shell prompt, but if for some reason you need renv to be a real script rather than a shell function, you can safely skip it.

To see exactly what happens under the hood for yourself, run renv init -.

Uninstalling R Versions

As time goes on, you will accumulate R versions in your $(renv root)/versions directory.

To remove old R versions, renv uninstall command to automate the removal process.

Alternatively, simply rm -rf the directory of the version you want to remove. You can find the directory of a particular R version with the renv prefix command, e.g. renv prefix 3.0.0.

Command Reference

See COMMANDS.md.

Environment variables

You can affect how renv operates with the following settings:

name	default	description
`RENV_VERSION`		Specifies the R version to be used. Also see `renv shell`
`RENV_ROOT`	`~/.renv`	Defines the directory under which R versions and shims reside. Also see `renv root`
`RENV_DEBUG`		Outputs debug information. Also as: `renv --debug <subcommand>`
`RENV_HOOK_PATH`	see wiki	Colon-separated list of paths searched for renv hooks.
`RENV_DIR`	`$PWD`	Directory to start searching for `.R-version` files.

Development

The renv source code is hosted on GitHub. It's clean, modular, and easy to understand, even if you're not a shell hacker.

Tests are executed using Bats:

$ bats test
$ bats/test/<file>.bats

Please feel free to submit pull requests and file bugs on the issue tracker.

License

The MIT License

jcrodriguez1989 / renv-installer