Switching From Bash To Fish

May 22, 2018 by mtchavez

I recently went through a painless transition from years of bash to fish shell in one evening. My bash setup has been stale for quite some time. I am mainly working in a bash terminal on a Mac and various Linux distributions. Bash, for me, has always been a bit of a mess to sort out the quirks of writing up scripts, loading in profile and configuration, and customizing the shell prompt. I had always put up with the quirks up until the other day when I decided to take the dive into Fish Shell.

Transitioning

Another common switch for people to make is changing to the latest text editor of the year. Having done this in the past as well I knew going into my shell switch that I would benefit from a similar approach as my past text editor switches.

  1. Jump right in and fail
  2. Run your current set up side by side
  3. Look into popular projects or resources in the ecosystem
  4. Reach out to people you know who already use it for advice

The Setup Details

For a macOS centric setup I was surprised how little I had to do to get my years of calloused bash setup and configuration covered with fish, and in a few ways exceeded.

Installing Fish

Fish is as simple as a brew install fish on macOS. The usual installation options are available for other environments. One of the post install messages you’ll see from homebrew is how to update your system shells to include Fish. Follow what it says by adding /usr/local/bin/fish to the /etc/shells file. Additionally change your default shell to Fish with chsh -s /usr/local/bin/fish

Fisherman

One of the things I never realized I wanted with Bash is some kind of sane way to configure common functionality from others or different communities. Plugins are one of the things that grab people’s attention to switch from bash to things like ZSH and Fish.

Fisherman is what I found to be the simplest and easiest plugin manager for Fish. It has a one line install with curl -Lo ~/.config/fish/functions/fisher.fish --create-dirs https://git.io/fisher and can be updated from itself going forward.

Outside of Fisherman there is Oh My Fish, which borrows its name from the popular Oh My ZSH project for ZSH. Fisherman itself is able to install any of the plugins that are a part of Oh My Fish so you won’t be left out choosing Fisherman for plugin management.

Plugins

Installing and managing plugins with fisherman is straightforward. You can install with fisher install bass. Additionally you can quickly remove with fisher remove nvm. The base set of plugins I went with are few and completely replaced all of my bash setup.

- omf/osx # macOS helper functions (probably not needed)
- omf/aws # AWS profile switcher (only for AWS users)
- fzf # Efficient key bindings (Requires fzf binary)
- edc/bass # Run bash from fish
- omf/foreign-env # Run commands in other envs
- omf/theme-scorphish # Theme
- nvm # Node version manager (Probably not needed)
- pipenv # Pipenv handling (Probably not needed)
- rbenv # Ruby version handling (Probably not needed)

Themes

Another thing modern shells make easier than bash is being able to adopt themes from others, or just theme in general. My bash prompt was always a little depressing compared to others who invested more time to get nifty things injected in their prompts. Oh My Fish has a comprehensive theme page that you an sift through to install one that catches your eye. Alternatively you can look into how to theme something of your own creation.

Then with fisherman you can simply fisher install some-theme and it will be applied to your shell.

Gotchas and Learnings

  1. Running bash scripts, both legacy and otherwise, is still really easy with the bass plugin. No need to convert those gnarly bash scripts over to fish just yet. Simply run bass "./that-one-script.sh".
  2. Exporting variables like export MY_KEY='asdf' is a little easier with set -x MY_KEY asdf where the -x is similar to exporting. You can erase the variable as well with set -e MY_KEY.
  3. Inline environment variables for commands or scripts can take some getting used to. I’ve grown accustomed to the bash approach here doing CACHE=false ./bin/runner. The fish equivalent here is a littler clunkier, in my opinion, but still has a good feel and readable env CACHE=false ./bin/runner.
  4. Configuration file lives in ~/.config/fish/config.fish by default and there is a ~/.config/fish/functions directory for shell functions like that of fisher for Fisherman.
  5. Setting your $PATH is pretty much the same by doing set PATH /usr/local/bin $PATH
  6. Args to your functions use $argv instead of $1, $2 etc.
  7. You can make functions with args using -a function foo -a bar echo $bar end

Outcome

All in all I have barely scratched the surface of what Fish can really do. My main goal was to try out a new shell that had things like autocompletion, themes, plugins, extensibility, and ease of use. Fish really does well with a lot of these out of the box and adding Fisherman on top for plugin management makes things seamless. One of my key takeaways, and big reason for writing this up, is that I was able to do this in a few hours one evening without much pain. The next week I ran into one or two minor roadblocks which were sorted out quickly and I was easily as productive, if not more, as with my previous bash shell setup.

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