- jlenv: Robust Julia management for your applications.

Use jlenv to pick a Julia version for your application and guarantee that your development environment matches production.

Powerful in development. Specify your app’s Julia version once, in a single file. Keep all your teammates on the same page. No headaches running apps on different versions of Julia. Just Works™ from the command line and with app servers like Pow. Override the Julia version anytime: just set an environment variable.

Rock-solid in production. Your application’s executables are its interface with ops. The Julia version dependency lives in one place—your app—so upgrades and rollbacks are atomic, even when you switch versions.

One thing well. jlenv is concerned solely with switching Julia versions. It’s simple and predictable. A rich plugin ecosystem lets you tailor it to suit your needs. Compile your own Julia versions, or use the julia-build plugin to automate the process. See more plugins.

Installation

Install jlenv. Note that this also installs julia-build, so you’ll be ready to install other Julia versions out of the box.
Run jlenv init and follow the instructions to set up jlenv integration with your shell. This is the step that will make running julia “see” the Julia version that you choose with jlenv.
Close your Terminal window and open a new one so your changes take effect.
That’s it! Installing jlenv includes julia-build, so now you’re ready to install some other Julia versions using jlenv install.

Basic GitHub Checkout

This will get you going with the latest version of jlenv without needing a systemwide install.

Clone jlenv into ~/.jlenv.
```
 git clone https://github.com/jlenv/jlenv.git ~/.jlenv
```
Optionally, try to compile dynamic bash extension to speed up jlenv. Don’t worry if it fails; jlenv will still work normally:
```
 cd ~/.jlenv
 src/configure
 make -C src
```
Add ~/.jlenv/bin to your $PATH for access to the jlenv command-line utility.
```
 echo 'export PATH="$HOME/.jlenv/bin:$PATH"' >> ~/.bash_profile
```
Ubuntu Desktop note: Modify your ~/.bashrc instead of ~/.bash_profile.

Zsh note: Modify your ~/.zshrc file instead of ~/.bash_profile.
Run ~/.jlenv/bin/jlenv init and follow the instructions to set up jlenv integration with your shell. This is the step that will make running julia “see” the Julia version that you choose with jlenv.
Restart your shell so that PATH changes take effect. (Opening a new terminal tab will usually do it.)
(Optional) Install julia-build, which provides the jlenv install command that simplifies the process of installing new Julia versions.

Upgrading with Git

If you’ve installed jlenv manually using Git, you can upgrade to the latest version by pulling from GitHub:

cd ~/.jlenv
git pull

How jlenv hooks into your shell

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

jlenv 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 jlenv init actually does:

Sets up your shims path. This is the only requirement for jlenv to function properly. You can do this by hand by prepending ~/.jlenv/shims to your $PATH.
Installs autocompletion. This is entirely optional but pretty useful. Sourcing ~/.jlenv/completions/jlenv.bash will set that up. There is also a ~/.jlenv/completions/jlenv.zsh for Zsh users.
Rehashes shims. From time to time you’ll need to rebuild your shim files. Doing this automatically makes sure everything is up to date. You can always run jlenv rehash manually.
Installs the sh dispatcher. This bit is also optional, but allows jlenv and plugins to change variables in your current shell, making commands like jlenv 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 jlenv to be a real script rather than a shell function, you can safely skip it.

Run jlenv init - for yourself to see exactly what happens under the hood.

Installing Julia versions

The jlenv install command doesn’t ship with jlenv out of the box, but is provided by the julia-build project. If you installed it either as part of GitHub checkout process outlined above, you should be able to:

# list all available versions:
jlenv install -l

# install a Julia version:
jlenv install v1.0.3

Alternatively to the install command, you can download and compile Julia manually as a subdirectory of ~/.jlenv/versions/. An entry in that directory can also be a symlink to a Julia version installed elsewhere on the filesystem. jlenv doesn’t care; it will simply treat any entry in the versions/ directory as a separate Julia version.

Uninstalling Julia versions

As time goes on, Julia versions you install will accumulate in your ~/.jlenv/versions directory.

To remove old Julia versions, simply rm -rf the directory of the version you want to remove. You can find the directory of a particular Julia version with the jlenv prefix command, e.g. jlenv prefix 1.0.0.

The julia-build plugin provides an jlenv uninstall command to automate the removal process.

Uninstalling jlenv

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

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

jlenv will still be accessible on the command line, but your Julia apps won’t be affected by version switching.

To completely uninstall jlenv, perform step (1) and then remove its root directory. This will delete all Julia versions that were installed under `jlenv root`/versions/ directory:

  rm -rf `jlenv root`

Environment variables

You can affect how jlenv operates with the following settings:

name	default	description
`JLENV_VERSION`		Specifies the Julia version to be used. Also see `jlenv shell`
`JLENV_ROOT`	`~/.jlenv`	Defines the directory under which Julia versions and shims reside. Also see `jlenv root`
`JLENV_DEBUG`		Outputs debug information. Also as: `jlenv --debug <subcommand>`
`JLENV_HOOK_PATH`	[See Authoring Plugins][/authoring-plugins#jlenv-hooks]	Colon-separated list of paths searched for jlenv hooks.
`JLENV_DIR`	`$PWD`	Directory to start searching for `.julia-version` files.

Development

The jlenv 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.

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