The fish shell is a command-line shell for Unix-like systems, written primarily in Rust with a modular crate architecture. It provides an interactive environment with syntax highlighting, autosuggestions, tab completions, and a scripting language. The core is in `src/` with builtins, parser, reader, history, job control, etc. External dependencies include PCRE2, nix, fluent for localization, and various Rust crates. The architecture is a single binary with many built-in commands and a large set of shell functions and completions. Key entry points: `fish` binary, `fish_indent`, `fish_key_reader`. Data flows: user input -> parser -> execution -> output. Completions are dynamically generated from shell functions and external command output. The project is actively maintained with a comprehensive test suite and CI/CD pipeline.
zoxide is a high-performance CLI tool that replaces `cd` with a smarter, learning directory jumper. It tracks directory access frequency and recency, ranks entries using a frecency algorithm, and allows instant navigation via partial keyword matching. The binary exposes subcommands for adding, querying, editing, importing, and removing entries, while shell-specific init scripts integrate hooks (prompt or PWD-based) to automatically record visited directories. Interactive selection via fzf and Space-Tab completions are supported on major shells (bash, zsh, fish, etc.). The codebase is a single Rust binary with a clean, modular architecture: a text-based database with atomic writes, a streaming query engine with lazy deletion, a trait-based import system for six external tools, and Askama-templated shell scripts. It demonstrates strong engineering practices: comprehensive CI/CD, cross-compilation for 12+ targets, shell script validation, and thorough test coverage including shell syntax checks.
Fisher is a pure-Fish plugin manager for the Fish shell. It provides a CLI with commands to install, update, remove, and list plugins, which can be sourced from local directories or remote tarballs (GitHub or GitLab). The entire implementation resides in a single `fisher.fish` function (~250 lines) that handles argument parsing, concurrent downloads, file placement, event emission, and state persistence via a `fish_plugins` file. The architecture is monolithic but well-structured, using Fish-specific features like universal variables and event hooks. No external dependencies beyond curl and tar are required, and the tool is designed to be zero-configuration and snappy. The test suite uses the Fishtape framework with a sample plugin (ponyo) to validate install/update/remove flows and event handling.