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1.0.7 • Public • Published


Introducing the fish-lsp, a Language Server Protocol (LSP) implementation for the fish shell language.

Why? 🐟


Feature Description Status
Completion Provides completions for commands, variables, and functions
Hover Shows documentation for commands, variables, and functions. Has special handlers for --flag, commands, functions, variables
Signature Help Shows the signature of a command or function
Goto Definition Jumps to the definition of a command, variable, or function
Find References Shows all references to a command, variable, or function
Rename Rename within matching global && local scope
Document Symbols Shows all commands, variables, and functions in a document
Workspace Symbols Shows all commands, variables, and functions in a workspace
Document Formatting Formats a document, full & selection
Document Highlight / Semantic Token Highlights all references to a command, variable, or function.
Command Execution Executes a server command from the client
Code Action Shows all available code actions
Code Lens Shows all available code lenses
Logger Logs all server activity
Diagnostic Shows all diagnostics
Folding Range Toggle ranges to fold text
Telescope Integration Integrates with the telescope.nvim plugin
CLI Interactivity Provides a CLI for server interaction. Built by fish-lsp complete <option>
Client Tree Shows the defined scope as a Tree
Indexing Indexes all commands, variables, and functions


Recommended Dependencies: yarn@1.22.22, node@21.7.1, fish@3.7.1

Building from source is the only currently recommended installation method, as we improve other methods of the installation process (Don't use releases or npm packages). Contributions to help enhance installation options are greatly appreciated!

  1. Clone the repo

    git clone
    # cd fish-lsp
  2. Install the dependencies & run the setup handler scripts

    yarn install
  3. Optional: Check that the project successfully compiled & linked

    fish-lsp --help # ./bin/fish-lsp --help

    fish-lsp --help


To properly configure fish-lsp, you need to define a client configuration after installing the language server. Client's typically only need the keys command, args/arguments, and filetypes to start a language server.

Client Configuration (Required)

Theoretically, the language-server should generally be compatible with almost any text-editor or IDE you prefer using. Feel free to setup the project in any fish-lsp-client of your choice, or submit a PR for new configurations.

  "fish-lsp": {
    "command": "fish-lsp",
    "filetypes": ["fish"],
    "args": ["start"]

Neovim client using coc.nvim configuartion, located inside coc-settings.json "languageserver" key

Server Configuration (Optional)

Specific functionality for the server can be set independently from the client. This allows for multiple configurations, to be defined and chosen via specific startup requirements (i.e., using the bind command with the function edit_command_buffer).

Environment variables

Generated by fish-lsp env --create

# fish_lsp_enabled_handlers <ARRAY>
# enables the fish-lsp handlers (options: 'asciiArt', 'formatting', 'logging',
# 'complete', 'hover', 'rename', 'definition', 'references', 'diagnostics',
# 'signatureHelp', 'codeAction', 'index')
set -gx fish_lsp_enabled_handlers

# fish_lsp_disabled_handlers <ARRAY>
# disables the fish-lsp handlers. (options: 'asciiArt', 'formatting', 'logging',
# 'complete', 'hover', 'rename', 'definition', 'references', 'diagnostics',
# 'signatureHelp', 'codeAction', 'index')
set -gx fish_lsp_disabled_handlers

# fish_lsp_commit_characters <ARRAY>
# array of the completion expansion characters. Single letter values only.
# Commit characters are used to select completion items, as shortcuts. (default: [])
set -gx fish_lsp_commit_characters

# fish_lsp_logfile <STRING>
# path to the logs.txt file (default: '~/path/to/fish-lsp/logs.txt')
set -gx fish_lsp_logfile

# fish_lsp_format_tabsize <NUMBER>
# amount of spaces in a tab character for the formatter provider (default: 4)
set -gx fish_lsp_format_tabsize

# fish_lsp_format_switch_case <BOOLEAN>
# keep case statements left aligned with switch block. (default: false)
set -gx fish_lsp_format_switch_case

# fish_lsp_all_indexed_paths <ARRAY>
# fish file paths/workspaces to include as workspaces (default: ['/usr/share/fish', "$HOME/.config/fish"])
set -gx fish_lsp_all_indexed_paths

# fish_lsp_modifiable_paths <ARRAY>
# fish file paths/workspaces that can be renamed by the user. (default: ["$HOME/.config/fish"])
set -gx fish_lsp_modifiable_paths

# fish_lsp_diagnostic_disable_error_codes <ARRAY>
# disable diagnostics for matching error codes (default: [])
# (options: 1001, 1002, 1003, 1004, 2001, 2002, 2003, 3001, 3002, 3003)
set -gx fish_lsp_diagnostic_disable_error_codes

# fish_lsp_max_background_files <NUMBER>
# maximum number of background files to read into buffer on startup (default: 1000)
set -gx fish_lsp_max_background_files

# fish_lsp_show_client_popups <BOOLEAN>
# show popup window notification in the connected client (default: true)
set -gx fish_lsp_show_client_popups

Command Flags

Both the flags --enable and --disable are provided on the fish-lsp start subcommand. By default, all handlers will be enabled.

# displays what handlers are enabled. Removing the dump flag will run the server.
fish-lsp start --disable complete signature --dump 

Further Server Configuration

Any flags will overwrite their corresponding environment variables, if both are seen for the fish-lsp process. For this reason, it is encouraged to wrap any non-standard behavior of the fish-lsp in functions or aliases.

Due to the vast possibilities this project aims to support in the fish shell, sharing useful configurations is highly encouraged.

How does it work?

If you're new to the concept of the Language Server Protocol (LSP), this section should be useful to help you grasp its core purpose and benefits.

📸 Check out this insightful video by TJ DeVries for an introduction to the subject. 📸

The LSP is designed to create a uniform approach for supporting a programming language across various development tools, moving beyond the confines of specific Text-Editor/IDE ecosystems. This standardization enhances a language's appeal by allowing developers to maintain consistent tooling support without needing to switch developer environments.

The core of this system is the interaction between a 'language server', which provides language services, and a 'language client', which consumes these services. The protocol facilitates this interaction, ensuring that any language client can leverage a well-defined set of features provided by the server.

Show a diagram to visualize a hypothetical fish-lsp process


Additional Resources

  • Contributing - documentation describing how to contribute to the fish-lsp project.
  • Roadmap - goals for future project releases.
  • Wiki - further documentation and knowledge relevant to the project
  • Discussions - interact with maintainers
  • Site - website homepage
  • Client Examples - testable language client configurations
  • Sources - major influences for the project


Special thanks to anyone who contributed to the project! Contributions of any kind are welcome!



Jaakko Paju
Jaakko Paju

Sean Perry
Sean Perry

Fabio Coatti
Fabio Coatti

Peter Cardenas
Peter Cardenas


This project follows the all-contributors specification.



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