# A novel Unix shell

[![GoDoc](http://godoc.org/github.com/elves/elvish?status.svg)](http://godoc.org/github.com/elves/elvish)
[![Build Status on Travis](https://travis-ci.org/elves/elvish.svg?branch=master)](https://travis-ci.org/elves/elvish)

This project aims to explore the potentials of the Unix shell. It is a work in
progress; things will change without warning. The [issues list](https://github.com/elves/elvish/issues) contains many things I'm working on.

## Screenshot

Elvish looks like this:

![syntax highlighting](https://raw.githubusercontent.com/elves/images/master/syntax.png)

## Prebuilt binaries

Up-to-date binaries for 64-bit [Linux](https://dl.elvish.io/elvish-linux.tar.gz) and [Mac OS X](https://dl.elvish.io/elvish-osx.tar.gz). Install with `sudo tar vxfz elvish-*.tar.gz -C /usr/bin`. See also [Building Elvish](#building-elvish).

## Getting Started

Put your startup script in `~/.elvish/rc.elv`.

Elvish mimics bash and zsh in a lot of places. The following shows some key differences and highlights, as well as some common tasks:

* Press Up to search through history. It uses what you have typed to do prefix match. To cancel, press Escape.

* Press Tab to start completion. Press Ctrl-N to start navigation mode. Likewise, pressing Escape gets you back to the default mode.

* Define aliases like `fn ls { external:ls --color $@ }`

* Elvish remembers which directories you have visisted. Use `dirs` to show the history. `jump x` jumps to the highest-scored directory containing `a`.

* Lists look like `[a b c]`, and maps look like `[&key1=value1 &key2=value2]`. Unlike other shells, lists never expands to multiple words, unless you explicitly splice it by prefixing the variable name with `$@`:
  ```
  ~> li=[1 2 3]
  ~> for x in $li; do echo $x; done
  [1 2 3]
  ~> for x in $@li; do echo $x; done
  1
  2
  3
  ```

* You can manipulate search paths through the special list `$paths`:
  ```
  ~> echo $paths
  [/bin /sbin]
  ~> paths=[/opt/bin $@paths /usr/bin]
  ~> echo $paths
  [/opt/bin /bin /sbin /usr/bin]
  ~> echo $env:PATH
  /opt/bin:/bin:/sbin:/usr/bin
  ```

* You can manipulate the keybinding through the map `$le:binding`. For example, this binds Ctrl-L to clearing the terminal: `le:binding[insert][Ctrl-L]={ clear > /dev/tty }` The first indexed is the mode and the same is the key. (Yes, the braces enclose a lambda.)

  Use `put $le:binding` to get a nice (albeit long) view of the current keybinding.

* Environment variables live in a separate `env:` namespace and must be explicitly qualified:
  ```
  ~> put $env:HOME
  ▶ /home/xiaq
  ~> env:PATH=$env:PATH":/bin"
  ```

* There is no interpolation inside double quotes (yet). Use implicit string concatenation:
  ```
  ~> name=xiaq
  ~> echo "My name is "$name"."
  My name is xiaq.
  ```

* A few floating-point arithmetic operations are builtin. However, you need to use prefix notation:
  ```
  ~> + 1 2
  ▶ 3
  ~> div (mul 2 3) 4
  ▶ 1.5
  ```

  Unfortunately we cannot use `*` and `/` in the shell.

* Functions are defined with `fn`. You can name arguments:
  ```
  ~> fn square [x]{
       mul $x $x
     }
  ~> square 4
  ▶ 16
  ```

* Output of some builtin commands start with a funny "▶". It is not part of the output itself, but shows that such commands output a stream of values instead of bytes. As such, their internal structures as well as boundaries between valued are preserved. This allows us to manipulate structured data in the shell; more on this later.


## More Screenshots:

Tab completion:

![tab completion](https://raw.githubusercontent.com/elves/images/master/completion.png)

Navigation mode:

![navigation mode](https://raw.githubusercontent.com/elves/images/master/navigation.png)


## Building Elvish

Go >= 1.5 is required. Linux is fully supported. It is likely to work on BSDs and Mac OS X. Windows is **not** supported yet.

The main binary can be installed using `go get github.com/elves/elvish`. There is also an auxiliary program called elvish-stub; install it with `make stub`. Elvish is funtional without the stub, but job control features depend on it.

If you are lazy and use `bash` for `zsh` now, here is something you can copy-paste into your terminal:

```
export GOPATH=$HOME/go
export PATH=$PATH:$GOPATH/bin
mkdir -p $GOPATH

go get github.com/elves/elvish
make -C $GOPATH/src/github.com/elves/elvish stub

for f in ~/.bashrc ~/.zshrc; do
    echo -e 'export GOPATH=$HOME/go\nexport PATH=$PATH:$GOPATH/bin' >> $f
done
```

[How To Write Go Code](http://golang.org/doc/code.html) explains how `$GOPATH` works.


## Name

In [roguelikes](https://en.wikipedia.org/wiki/Roguelike), items made by the elves have a reputation of high quality.  These are usually called **elven** items, but I chose **elvish** for an obvious reason.

The adjective for elvish is also "elvish", not "elvishy" and definitely not "elvishish".

## Test coverages:

|Package|Coverage|
|-------|--------|
|edit|[![edit](https://gocover.io/_badge/github.com/elves/elvish/edit/)](https://gocover.io/github.com/elves/elvish/edit/)|
|eval|[![eval](https://gocover.io/_badge/github.com/elves/elvish/eval/)](https://gocover.io/github.com/elves/elvish/eval/)|
|glob|[![glob](https://gocover.io/_badge/github.com/elves/elvish/glob/)](https://gocover.io/github.com/elves/elvish/glob/)|
|parse|[![parse](https://gocover.io/_badge/github.com/elves/elvish/parse/)](https://gocover.io/github.com/elves/elvish/parse/)|
|run|[![run](https://gocover.io/_badge/github.com/elves/elvish/run/)](https://gocover.io/github.com/elves/elvish/run/)|
|store|[![store](https://gocover.io/_badge/github.com/elves/elvish/store/)](https://gocover.io/github.com/elves/elvish/store/)|
|stub|[![stub](https://gocover.io/_badge/github.com/elves/elvish/stub/)](https://gocover.io/github.com/elves/elvish/stub/)|
|sys|[![sys](https://gocover.io/_badge/github.com/elves/elvish/sys/)](https://gocover.io/github.com/elves/elvish/sys/)|
|util|[![util](https://gocover.io/_badge/github.com/elves/elvish/util/)](https://gocover.io/github.com/elves/elvish/util/)|