Welcome to the lab.

Over the past few months I’ve been playing with Fish, the Friendly Interactive SHell, and I’ve posted a couple of times on the topic. I think I’m sold on it now, and you’ll probably be seeing a lot more Fish posts than Bash ones (though I’ll try to offer Bash equivalents when possible).

So I’ve officially chsh‘d to /usr/local/bin/fish and am 100% comfortable using it day to day. For the record, I did spend some time with Zsh as well, but it just didn’t tickle the same fancy as Fish has for me.

Here are some of my tips, tricks, and observations since my last post.

Back in April I posted a short script for keeping track of the various build systems I use in my projects. You know when you open a directory you haven’t worked on for a while and there’s a Gulp file, a Rakefile, a node_modules folder, and various other cruft that means you’ll have to dig through to recall what commands you were using to build and deploy the project? Or when you know there were specific flags you were using to get the build to work, but you never got around to automating them? It’s for those situations, and other general sanity.

Over the rest of this year I’ve slowly modified and expanded the script as I’ve wanted it to do things differently or better. I’ve been hesitant to post the results because it really feels like something nobody else is going to need and it’s entirely possible that I’ve put too much time into it already. I did stop myself before turning it into a fully packaged gem, so good on me.

In my last post on the Fish shell, I brazenly stated that “because of the way that Fish handles the prompt function, there’s no easy way to hook it without modifying the original theme files.” That was 100% incorrect, as I figured out the next day.

Fish has the ability to specify that any function act as an event handler. You can attach to the event fish_prompt to have the function run right before the prompt displays. So my revised function in my init file is:

function __should_na --on-event fish_prompt
  set -l cmd (history --max=1|awk '{print $1;}')
  set -l cds cd z j popd g
  if contains $cmd $cds
    test -s (basename $PWD)".taskpaper" && ~/scripts/fish/na
  end
end

Now I no longer need to edit the theme files directly at all, which is much more how I’d prefer things to be. As an alternative to fish_prompt, you can also attach to variables changing, which means you can use PWD to run the function any time the working directory changes. That would look like:

function __should_na --on-variable PWD
	...

Also, any function can use the emit command to add its own hook. The example from the docs is nice and succinct:

function event_test --on-event test_event
    echo event test: $argv
end

emit test_event something

This is one area where the Fish documentation seems lacking: there’s no list of available hooks nor (that I can find) any way to retrieve a list of emitted events in the shell. It’s been trial and error for me thus far. Hopefully someone will correct me if I’m wrong here. Update, someone (evanrelf) did correct me in the comments: you can find a list of all named events using function -h.

Ok, so that’s an extended correction to my last post, but it’s a cool enough aspect of Fish that it seemed worth covering on its own.

Given that Apple has already switched the default shell in Catalina from Bash to Zsh, I’ve been thinking I really need to expand from Bash. Don’t get me wrong, I love Bash and I’ve spent years molding it to my liking. The amount of time I’ve put into it and the ease with which that investment allows me to use it has always made switching to anything else seem, well, like a waste of time. But now I feel stuck. To that end, I’ve been stretching out and trying to shake off my fear of getting to know other shells.

I decided to spend some time getting comfortable with Zsh and Fish (the Friendly Interactive SHell). I started with Fish, building a configuration on weekends. Three weekends now and I’m comfortable enough to use it as my regular shell during the week.

Fish features advanced autosuggestion and expansions, does cool syntax highlighting, offers a “sane” scripting toolset, has an array of existing plugins and themes, and even sports a browser-based configuration tool that’s pretty awesome. So here are some random notes from my travels. This is a journal, not a tutorial, containing my impressions and a few tips.