Fish shell

A command line shell that does not think that the problem is you

Not the aquatic creature, but rather the command-line doohickey, which is not as shit as the other ones. I’m gradually transitioning to fish, after accidentally losing a lot of precious data due to a quirk in bash syntax. Long boring story. It’s time for new, exciting, different stupid errors.

fish has a strong fanbase and an opinionated design. If you dislike those design opinions, at least you might appreciate it has a healthy degree of sarcasm in said opinions, which sarcasm is sorely absent from the drearily earnest nerdview of your typical project. You might also hold that having any kind of opinion is better than the design-by-accumulation-of-cruft which structures traditional command-line shells.



Plugins are managed via oh my fish

curl -L | fish

or by fisher.

curl --create-dirs -sLo ~/.config/fish/functions/

The omf manual is surly. See a helpful blogpost. I am currently running omf, but since it intrusively changed my prompt I am grumpy at it. However, I got a better one, spacefish.

omf install spacefish

It does need the wacky powerline fonts.

sudo apt-get install fonts-powerline

There are various useful plugins that are not purely cosmetic; For example fzf adds fuzzy history search.


Modifying the search PATH

Adding a path? Say it’s /usr/local/bin. Put

set -gx PATH /usr/local/bin $PATH

in ~/.config/fish/, OR

set -U fish_user_paths /usr/local/bin $fish_user_paths

Removing a path?

set -gx PATH (string match -v /usr/local/bin $PATH)

🏗 explain the difference between $PATH and $fish_user_path which will depend upon me understanding how the content of $PATH magically replenishes itself and the difference between universal and global variables.

Modifying any settings with GUI


Traditional config

Put commands in ~/.config/fish/

homebrew compatibility on ubuntu

Since I use fish shell as my default but ubuntu automatically executs the bash startup script .profile on login I ran into the following errors on login, when it tried to run the fish init in a bash process:

bash: set: -g: invalid option
set: usage: set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg ...]
bash: set: -g: invalid option

This is maybe related to an intermittently reported bug in homebrew. The fix that worked for me was to change the automatically-added line in .profile to be

eval $(SHELL=bash /bin/brew shellenv)

and to add

eval (env SHELL=fish /bin/brew shellenv)

to ~/.config/fish/

Python environments


if you are still using virtualenv on python you will need virtualfish to replace python’s Or switch to native python3 venv, which is more or less the same thing but works better and doesn’t support python 2. But if you need to support python 2 at this stage it’s because you are in some weird enterprise environment with horrid legacy software, so hopefully you can farm this problem out to the tech support team?

Using anaconda python

You need to do some extra setup to use conda with fish. Specifically, add the line

source ~/miniconda3/etc/fish/conf.d/

into ~/.config/fish/

(Replace ~/miniconda3/ with the output of conda info --root if you used a non-standard install location)

More recently conda has change to make this even simpler:

~/miniconda3/bin/conda init fish

Vars, expansions, extensions, suffixes

Use classic subcommands.

for file in (ls *.html)
  mv $file (basename $file .html).txt

or string expansion

for file in (ls *.html)
  mv $file (string replace -r "\.html\$" .txt $file)

For loops

while true
  echo "Loop forever"

Test exit status

Similar to bash.

if test $status -eq 0
  echo yeah

To simply execute the second command if the first succeeded the command you want is and, which is hard to google for:

../bin/ foo; and cp foo ~/Dropbox/

Temporary variable setting uses env


Aliases, custom commands

Command, alias, or abbr?

  • Command allows overwriting a command.
  • Alias makes an alias, but is lacking autocomplete.
  • Abbr makes a sort of alias that will expand out and support autocomplete.