A novel Unix shell

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 contains many things I'm working on.

Screenshot

Elvish looks like this:

Prebuilt binaries

Up-to-date binaries for 64-bit Linux and Mac OS X. Download the archive and install with sudo tar vxfz elvish-*.tar.gz -C /usr/bin.

See also 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 $@ }

• 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, which is indexed by the mode name and then by the key name.

  For example, this binds Ctrl-L to clearing the terminal: le:binding[insert][Ctrl-L]={ clear > /dev/tty } (yes, the braces enclose a lambda).

  Use put $le:binding to get a pretty-printed (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 builtin directory history. Use dirs to show the history. jump x jumps to the highest-scored directory containing a.

• 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 arithmetic operations are builtin. However, you need to use prefix notation:

  ~> + 1 2
  ▶ 3
  ~> mul `+ 1 2` 3
  ▶ 9
  

• Functions are defined with fn. You can name arguments in the definition:

  ~> 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 Screenshots:

Tab completion:

Navigation mode:

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 explains how $GOPATH works.

Name

In roguelikes, 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
eval
glob
parse
run
store
stub
sys
util