Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?


Failed to load latest commit information.
Latest commit message
Commit time


closh - Bash-like shell based on Clojure

Chat about Closh at Zulip Join the chat at Build status on CircleCI GitHub release

Status update 2022: Closh is now on hiatus.
Although the initial proof of concept turned out promising, it would take much more work to make it a robust tool that could be relied upon by a wider audience.
For now I recommend using fish as an interactive shell and babashka for scripts.

Closh combines the best of traditional unix shells with the power of Clojure. It aims to be a modern alternative to bash.

Demo showing how to execute commands and using Clojure to manipulate outputs in shell:

closh demo screencast

Why try to reinvent bash?

  • Bash has obscure syntax for non-trivial operations and lots of WTF moments.
  • It treats everything as text while we mostly need to manipulate structured information.
  • It is a large codebase which makes it difficult to hack on it and try innovative ideas. Which is one of the reasons why the shell did not improve much in recent decades.
  • Traditional shells are limited in terms of presentation and discoverability, what if we could bring back richer environment as imagined by lisp machines?

Why shell based on Clojure(Script)?

  • Clojure's has a simple syntax and well-thought design which makes it pleasurable to work with.
  • Its extensive collection of powerful functions for data manipulation is suitable to provide solutions for daily tasks.
  • Write shell scripts in a language you use daily for development so you don't have to google arcane shell constructs every time you need to do anything but simplest tasks.
  • Less amount and more composable code allows to experiment with new features and ideas.

Warning: Closh is still in a early stage and under a heavy development, has many rough edges and is subject to change a lot. Closh is tested on Linux, should run on macOS too.

Community and Contribution

If you have feedback about a specific feature or found a bug please open an issue.
Use reddit for general discussion and to share scripts and workflows. Chat room is on zulip or gitter.

If you would like to contribute take look at open issues. Leave a comment if you find anything interesting and we can improve the project together.


Windows proper is currently NOT supported, but it should run under WSL 2. If you know your way around with Windows, we need your help (see #54).

Try closh online in the browser without installing anything.

Clojure/JVM version

Download the jar file from the releases page and run it with:

java -jar closh-zero.jar

The jar file also contains a special header, so once you make it executable you can run it directly:

chmod +x closh-zero.jar

It can also run with clojure CLI:

clojure -Sdeps '{:deps {closh {:git/url "" :tag "v0.5.0" :sha "6a7c0aa293616e2d28f7f735e915a301e44d2121"}}}' -m

ClojureScript/Lumo version

Install closh (requires Node.js version 9.x, support for version 10 is in progress, see #113):

npm install -g closh

If you get a permission error then try:

npm install -g closh --unsafe-perm

To install development version from master branch:

npm i -g dundalek/closh

Quick Start

Start the shell:


Run simple commands like you are used to:

$ echo hi

$ git status

$ ls -l *.json

Commands starting with a parenthesis are evaluated as Clojure code:

$ (+ 1 2)
; => 3

The power comes from combining shell commands and Clojure:

$ echo hi | (clojure.string/upper-case)
; => HI

$ ls *.json |> (reverse)

; Count number of files grouped by first letter sorted by highest count first
$ ls |> (group-by first) | (map #(update % 1 count)) | (sort-by second) | (reverse)

If you like closh you can set it as your default shell.

Be careful and first test closh from other shell to make sure it works on your machine so you don't get locked out of shell (after chsh you need to log out and log back in for changes to take effect):

which closh | sudo tee -a /etc/shells
chsh -s $(which closh)

For the JVM version you can make it the default shell similarly like:

chmod +x $closh
echo $closh | sudo tee -a /etc/shells
chsh -s $closh



Terminal UI improvements and exploration

Explore innovate UI ideas, explore what a shell could become and all possibilities within an ASCII terminal. The goal is to reimagine what people think a command line interface is without having to lose its core power.

  • Try to integrate Liquid as the editor interface, which would enable us:
    • Better and more flexible readline experience
    • Customizable key bindings
  • Try to explore Trikl for building interactive command-line interfaces
  • Data helpers that automatically parse command output into data structures
  • Automatic abbreviation suggestion
  • Explore launcher functionality similar to Alfred, Lacona and others

More UI exploration

Explore if we could take shell power and functionality and lift it from the boundaries set by ASCII terminals.

Stabilization and performance

I hope that new UI ideas above will get people excited and interested. After that we should work on stabilization and adding all the remaining features people are used to from traditional shells.

  • Implement a low-level native pipeline library to improve performance
  • Make it more robust and better error handling
  • Job control


JVM version (CLJ)

Lumo version (CLJS)

  • No script mode
  • No syntax highlighting
  • Prompt quirks
  • Synchronous execution hacks (via deasync library)


Clone the repo and install dependencies

git clone
cd closh
npm install

Run the cljs app

npm start

Run the clj app

clojure -m

Run tests once

npm run test

Re-run tests on change

npm run test-auto

Manual Java builds

Run npm run pkg-java. The resulting binary will be in target/closh-zero.jar.


Thank you for the support:


Copyright & License

Copyright (c) Jakub Dundalek and contributors

Distributed under the Eclipse Public License 1.0 (same as Clojure).

Logo created by @batarian71 under CC BY 4.0.