elvish/README.md
2016-02-23 00:53:40 +01:00

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# 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/)|