The fish shell is amazing – Mairo Rufus – The faster you fail, the faster you learn

Date: Written on November 8, 2021

Location: rmpr.xyz

I’ve been lurking the fish shell for a couple of years now (and the nushell but it is another story for another time). Not so long ago, I decided to try it, and it’s simply… amazing. If I had to state one feature that makes me like to use it, it’ll be the autocompletion, hands down. It’s the first time I just take a shell and without customization it’s pleasing to use.

Features

Some notable features I want to mention:

  • The default colorscheme: when you type something invalid it’s red, blue when not

  • Smart tab completion not only for the commands but for the arguments as well, and it apparently does that by parsing man pages. The autocompletion is also contextual, depending on where you are, it suggests different things.

  • Floating point calculation directly inside the shell, not super important, but I used to use a REPL or bc for that

  • You can configure your shell using a web interface! Just run fish_config

What about Plugins?

On my previous shells I used bash-it and oh-my-zsh. While those are amazing projects, they still need configuration to get things to work really well. And if you want to match fish’s level, you will need to install a lot of plugin and/or write quite a few lines of code. With fish you get that for free. Nevertheless, there are some plugins manager, oh-my-fish, fisher and Fundle. To be honest, I didn’t find them super useful because the only plugin I use is the starship prompt and it’s available in the Fedora repo anyway. For those interested, here is a comparison between fisher, omf and fundle it might be a bit biased since it’s by fisher’s author. But those seemed to me like valid points.

I used oh-my-zsh with powerlevel10k because it’s very fast. When switching to fish, I felt I had to choose between starship and tide. I wish I could say more things on that, but I chose starship solely because it is on the Fedora repo :p but it’s crazy fast though.

Some quirks (that might actually not be quirks)

The first thing you need to know, fish is not POSIX compliant, don’t expect your previous scripts to work at all. The syntax is different, and arguably better. For example the for loop:

with fish:

for i in *.pdf
    echo $i
end

With bash/zsh:

for i in *.pdf;
do
    echo $i;
done

No more fi, esac or done.

Although I didn’t face anything (source bin/activate.fish works like a charm), if you have issues activating Python virtual environments, you can have a look at virtualfish

Closing thoughts

In my opinion, fish is not geared towards shell scripting, it’s interactivity is simply unmatched in any current shells that I know of. If you are more interested in a better shell scripting experience, you might want to have a look at the oil shell instead. Don’t get me wrong, you still need to learn bash at a decent level as it is what you’ll probably stumble upon the most (in containers, virtual environments, vanilla servers, …), but this shouldn’t prevent you from stepping up your game. If you liked this post, check out this awesome piece by Julia Evans. This is the first article of the serie about mouseless computing, I felt like it’s kinda useful to have this as an entry point. Stay tuned for the next one.