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A new system shell that uses theJanet programming languagefor high level scripting while also supporting the things we love about sh.

Minimal knowledge of janet is required for basic shell usage,but know that as you become more familiar with janet, your shell will gain the power of:

• A powerful standard library.
• Functional and imperative programming.
• Powerful lisp macros.
• Runtime loadable extension modules written in C/C++/rust/zig...
• Coroutines and exceptions.
• Much much more.

Help develop janetshdonate via paypal

Janetsh development has slowed and I am not actively working on it for now.Some of it is no longer compatible with the latest janet release.

That being said, I consider janetsh a successful proof of concept and place to drawcode and ideas from whenever the next attempt at fixing shells gets my attention.

One potential avenue for janetsh2 in the future is to integrate janet syntaxwith the shell library:

https://github.com/emersion/mrsh

If we do this, we can have POSIX compatibility when we need it, as well as avoid implementingmost of the complexity in a shell, and can instead focusing on delivering on the importantideas of janetsh.

demo source codedemo rc file

As you would expect:

$ ls -la | head -n 3total 100drwxr-xr-x 1 ac users   220 May 13 20:16 .drwxr-xr-x 1 ac users   760 May 12 21:08 ..0$ echo foo > /dev/null0$ sleep 5 &@{:pgid 82190 :procs @[@{:args @["sleep" "5"]      :pid 82190      :stopped false      :redirs @[]}]}$ rm ./demos/*.gif0

$ (map string/ascii-upper ["functional" "programming"])@["FUNCTIONAL" "PROGRAMMING"]$ (defn lines [s] (string/split "\n" s))<function lines>$ (lines ($$ ls | head -n 3))@["build.sh" "demos" "janetsh" ""]$ echo (reduce + 0 [1 2 3])60

$ (string/ascii-upper ($$ echo command string capture))"COMMAND STRING CAPTURE\n"$ ($$_ echo trimmed capture)"trimmed capture"$ (if (= 0 ($? touch /tmp/test.txt)) "success")"success"$ (if ($?? touch /tmp/test.txt) "shorthand success")"shorthand success"

$ (try    (do      ($ rm foo.txt)      ($ rm bar.txt)      ($ rm baz.txt))    ([err] (print "got an error:" err)))

$ (each f files (sh/$ wc -l [f]))

$ ls | head -n 3 | (out-lines string/ascii-upper)BUILD.SHDEMOSJANETSH0

Hopefully in the future this sparse reference set will become more polished, but for nowthe following snippets may help advanced users play with the shell in it's current state.

Janetsh runs a user rc script~/.janetsh.rc at startup when in interactive mode. Thisfile can changed or disabled via command line flags.

Janetsh runs/etc/janetsh.rc on any run if it exists. This file can be changed or disabled viacommand line flags.

Users can set a custom prompt:

(set *get-prompt* (fn [p] "$ "))

p is a janet standard library parser, which can be used to find the current repl nesting level.

Users can set a custom line completion function:

(set *get-completions*  (fn [line word-start word-end]    @["your-completion"]))

By default janetsh does not store any history to avoid accidental information leaks.

To enable history add the following line to your janet rc file:

(set *hist-file* (first (sh/expand "~/.janetsh.hist")))

A list of running jobs can be found in the variable sh/jobs, eachof which is a janet table containing the current state of a user job/pipeline.

The sh package has some functions for manipulating jobs, suchas putting them in the foreground, or terminating them. Thisis not a stable interface for now, so you will need to read the code yourselffor documentation.

Some examples:

vim...Ctrl+Z$ (sh/fg-job (first sh/jobs))...Ctrl+Z$ sleep 60 &$ (sh/terminate-all-jobs)$ (sh/disown-job (sh/$ sleep 60 &))

Here is an example of defining a new builtin shell command.

(defn- make-my-builtin  []  @{    :pre-fork      (fn pre-fork        [self args]        (print "hello from shell process"))    :post-fork      (fn post-fork        [self args]        (print "hello from child process"))  })(put sh/*builtins* "my-builtin" make-my-builtin)

It is important to catch any errors and only report themfrom the child process. This means builtins can manipulate theshell internal state, but still behave like regular processesfor the purpose of exit codes, pipes and job control.

For the default build you will need pre released janet 1.0.0 built from source, readline and pkg-config installed on your system, then you can run:

./configure && make install

If you want libedit instead of readline you can build with:

./configure --with-pkg-config-libedit

If you don't want to depend on readline or libedit, you can use the bundled emulation.

./configure --with-readnoise

You can also manually specify header paths, install paths and flags.

Try./configure --help for a list of options.

Internally janetsh is implemented as a low level C library for the janet programminglanguage, a janet library and a small launcher that does some necessary setup/teardown.

The janet main implementation is a set of janet functions and macros that perform shelljob control, control user input and manage your command pipelines.

At the highest level the user is presented with aninteractive repl interface which implicitly invokes a janet macroto give janet the familiar sh syntax. You can escape this implicitmacro by prefixing a line with '(' which reverts to regular janet mode.

Janetsh can also be used for scripting, in which case it acts a small job control runtime andlauncher for janet programs.

The project is at the proof of concept phase and is onlyusable by people brave and willing to fix things forthemselves.

The author would love donations or help from fellow developers to keep things going forward.Donations will go towards living expenses while developing janetsh and providing upstream support forthe janet programming language issues that affect Janetsh.

This project takes considerable time an effort, pleasedonate here via paypal to keep the project alive.

At your request with each donation leave a message and if appropriate, it will be included below.

You - Your message

This project is being built with care by Andrew Chambers.

Special thanks to Calvin Rose for creating the Janet programming language.

Thanks to the authors ofclosh,rashandxonsh for providing inspiration for the project.