virtualfish¶

Installing¶

1. Make sure you’re running Fish 2.x. If you’re running an Ubuntu LTS release that has an older Fish version, install Fish 2.x via the fish-shell/release-2 PPA.

2. Install virtualfish by running pip install virtualfish.

3. Add the following to your ~/.config/fish/config.fish:

   eval (python -m virtualfish)
   

   If you want to use virtualfish with plugins, list the names of the plugins as arguments to the virtualfish loader:

   eval (python -m virtualfish compat_aliases)
   

   Note: If your config.fish modifies your $PATH, you should ensure that you load virtualfish after those modifications.

4. Customize your fish_prompt

Customizing Your fish_prompt¶

virtualfish doesn’t attempt to mess with your prompt. Since Fish’s prompt is a function, it is both much less straightforward to change it automatically, and much more convenient to simply customize it manually to your liking.

The easiest way to add virtualenv to your prompt is to type funced fish_prompt, add the following line in somewhere:

if set -q VIRTUAL_ENV
    echo -n -s (set_color -b blue white) "(" (basename "$VIRTUAL_ENV") ")" (set_color normal) " "
end

Then, type funcsave fish_prompt to save your new prompt to disk.

Commands¶

• vf new [<options>] <envname> - Create a virtualenv. Note that <envname> must be last.
• vf ls - List the available virtualenvs.
• vf activate <envname> - Activate a virtualenv. (Note: Doesn’t use the activate.fish script provided by virtualenv.)
• vf deactivate - Deactivate the current virtualenv.
• vf rm <envname> - Delete a virtualenv.
• vf tmp [<options>] - Create a temporary virtualenv with a randomly generated name that will be removed when it is deactivated.
• vf cd - Change directory to currently-activated virtualenv.
• vf cdpackages - Change directory to the currently-activated virtualenv’s site-packages.
• vf addpath - Add a directory to this virtualenv’s sys.path.
• vf all <command> - Run a command in all virtualenvs sequentially.
• vf connect - Connect the current working directory with the currently active virtualenv. This requires the auto-activation plugin to be enabled in order to have any effect besides creating a .venv file in the current directory.

If you’re used to virtualenvwrapper’s commands (workon, etc.), you may wish to enable the Virtualenvwrapper Compatibility Aliases (compat_aliases) plugin.

Using Different Pythons¶

By default, the environments you create with virtualenv (and, by extension, virtualfish) use the same Python version that virtualenv was installed under, which will usually be whatever your default system Python is.

If you want to use something different in a particular virtualenv, just pass in the --python PYTHON_EXE (-p for brevity) argument to vf new, where PYTHON_EXE is any Python executable, for example:

vf new -p python3 my_python3_env
vf new -p /usr/bin/pypy my_pypy_env

Configuration Variables¶

All of these must be set before virtual.fish is sourced in your ~/.config/fish/config.fish.

• VIRTUALFISH_HOME (default: ~/.virtualenvs) - where all your virtualenvs are kept.
• VIRTUALFISH_DEFAULT_PYTHON - The default Python interpreter to use when creating a new virtualenv; the value should be a valid argument to virtualenv‘s --python flag.

Virtualenvwrapper Compatibility Aliases (compat_aliases)¶

This plugin provides some global commands to make virtualfish behave more like Doug Hellman’s virtualenvwrapper.

Auto-activation (auto_activation)¶

With this plugin enabled, virtualfish can automatically activate a virtualenv when you are in a certain directory. To configure it to do so, change to the directory, activate the desired virtualenv, and run vf connect.

This will save the name of the virtualenv to the file .venv. Virtualfish will then look for this file every time you cd into the directory (or pushd, or anything else that modifies $PWD).

Global Requirements (global_requirements)¶

Keeps a global requirements.txt file that is applied to every existing and new virtualenv.

Projects (projects)¶

This plugin adds project management capabilities, including automatic directory switching upon virtual environment activation. Typically a project directory contains files — such as source code managed by a version control system — that are often stored separately from the virtual environment.

The following example will create a new project, with a matching virtual environment, both named YourProject:

vf project YourProject

The above command performs the following tasks:

1. creates new empty project directory in PROJECT_HOME (if there is no existing YourProject directory within) and changes the current working directory to it
2. creates new virtual environment named YourProject and activates it

To work on an existing project, use the vf workon <name> command to activate the specified virtual environment and change the current working directory to the project of the same name. For cases in which the project name differs from the target virtualenv name, you can manually specify which virtualenv should be activated for a given project by creating a .venv file inside the project root containing the name of the corresponding virtualenv.

Variables¶

Virtualenv currently provides one global variable to allow you to inspect its state. (Keep in mind that more are provided by plugins.)

• VIRTUAL_ENV - Path to the currently active virtualenv.
  • Tips: use basename to get the virtualenv’s name, or set -q to see whether a virtualenv is active at all.

Events¶

virtualfish emits Fish events instead of using hook scripts. To hook in to events that virtualfish emits, write a function like this:

function myfunc --on-event virtualenv_did_activate
    echo "The virtualenv" (basename $VIRTUAL_ENV) "was activated"
end

You can save your function by putting it in .config/fish/config.fish, or put it anywhere Fish will see it before it needs to run. (Note: saving it with funcsave won’t work.)

Some events are emitted twice, once normally and once with the name of the virtualenv as part of the event name. This is to make it easier to listen for events relevant to one specific virtualenv, for example:

function myfunc --on-event virtualenv_did_activate:my_site_env
    set -gx DJANGO_SETTINGS_MODULE mysite.settings
end

The full list of events is:

• virtualenv_did_setup_plugins
• virtualenv_will_activate
• virtualenv_will_activate:<env name>
• virtualenv_did_activate
• virtualenv_did_activate:<env name>
• virtualenv_will_deactivate
• virtualenv_will_deactivate:<env name>
• virtualenv_did_deactivate
• virtualenv_did_deactivate:<env name>
• virtualenv_will_create
• virtualenv_did_create
• virtualenv_did_create:<env name>

Why isn’t Virtualfish written in Python?¶

Mostly, for the same reasons virtualenvwrapper is.

Does Virtualfish work with Python 3? What about PyPy?¶

Yes! In fact, you can create Python 3 virtualenvs even if your system Python is Python 2, or vice versa, using the --python argument (see the Usage section for full details).

Why does Virtualfish use Virtualenv and not pyvenv?¶

pyvenv may be the new shiny, but it can only be run from Python 3 and can only create Python 3 environments. In contrast, virtualenv fully supports Python 2 and 3, as discussed above. So, we can’t use pyvenv on its own.

It’s been suggested that we could use both, but that would add complexity for no real benefit. If pyvenv added new, broadly useful features not in virtualenv, or if virtualenv stopped working on Python 3, or if Python 2 went out of widespread use, this might change, but for now virtualenv is the best choice.

Why doesn’t Virtualfish use activate.fish?¶

Virtualfish uses its own internal virtualenv activation code instead of the activate.fish file that comes with every virtualenv for two main reasons. One is that when Virtualfish was originally written, activate.fish didn’t actually work. The second reason, which is still valid today, is that activate.fish tries to modify your fish_prompt function.

Because fish_prompt is a function and not a variable like in most other shells, modifying it programmatically is not trivial, and the way that virtualenv accomplishes it is more than a little hacky. The benefit of it being a function is that the syntax for customising it is much less terse and cryptic than, say, PS1 on Bash. This is why Virtualfish doesn’t attempt to modify your prompt, and instead tells you how to do it yourself.

Prompts¶

• Both bobthefish and scorphish themes for Oh My Fish! support virtualfish.