obsidian/wiki/dotfiles/fish-shell-intro.md

title	aliases	tags	sources	created	updated
Fish Shell 4.6 — Introduction & Setup	fish-shell fish-intro fish-setup	fish shell terminal dotfiles cli	raw/Introduction — fish-shell 4.6.0 documentation.md	2026-04-17	2026-04-17

What is Fish?

Fish (friendly interactive shell) is a shell focused on usability and interactive use. It works out-of-the-box without configuration.

Headline features:

• Syntax highlighting, autosuggestions, tab completion with navigable/filterable lists
• No config required — ready immediately after install
• Easy scripting with a clean, learnable syntax

Starting & Exiting

fish        # start a fish session inside another shell
exit        # end the session

Making Fish Your Default Shell

Option A — terminal emulator setting (safest): point your terminal (WezTerm, Kitty, iTerm2) to /usr/local/bin/fish directly in its config.

Option B — login shell (riskier, see warning below):

command -v fish | sudo tee -a /etc/shells   # register fish
chsh -s "$(command -v fish)"                # set as login shell

[!warning] Login shell caveat Some Linux distros require the login shell to be Bourne-compatible and source /etc/profile. Fish is not Bourne-compatible — this can break PATH and other env vars. Prefer the terminal emulator approach on Linux.

Configuration Files

File	Purpose
~/.config/fish/config.fish	Main config — runs every shell startup
~/.config/fish/conf.d/*.fish	Auto-sourced before config.fish

Use guards to scope behavior:

if status --is-interactive
    # interactive-only setup (prompt, aliases, etc.)
end

if status --is-login
    set -gx PATH $PATH ~/linux/bin
end

Prefer fish_add_path over manual PATH manipulation — it deduplicates automatically:

fish_add_path ~/linux/bin

Shebang Line for Fish Scripts

#!/usr/bin/env fish
echo Hello from fish $version

Use env fish (not a hardcoded path) so the script works regardless of where fish is installed. The shebang is only needed when executing a script directly — not when running with fish /path/to/script.

Exit Event Handler

function on_exit --on-event fish_exit
    echo fish is now exiting
end

Inspecting Your Config Changes

fish_delta   # shows what you changed from fish's defaults

Key Takeaways

• Fish is batteries-included: syntax highlighting, autosuggestions, and completions work with zero config
• Don't set fish as login shell on Linux unless you know your distro supports it — use terminal emulator config instead
• Config lives in ~/.config/fish/config.fish; modular snippets go in conf.d/
• Use fish_add_path instead of manually editing $PATH
• Script shebangs should use #!/usr/bin/env fish for portability
• fish_delta reveals your customizations vs defaults

Related

• wiki/dotfiles/linux-terminal-ricing — Kitty + Fish + Tide full setup guide
• wiki/dotfiles/terminal-cheatsheet — daily stack reference with fish/zsh
• wiki/dotfiles/wezterm-config — set fish as the default program in WezTerm

Sources

• raw/Introduction — fish-shell 4.6.0 documentation.md (fishshell.com/docs/current/index.html)