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156 lines
6.5 KiB
Markdown
156 lines
6.5 KiB
Markdown
# A novel Unix shell
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[](http://godoc.org/github.com/elves/elvish)
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[](https://travis-ci.org/elves/elvish)
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This project aims to explore the potentials of the Unix shell. It is a work in
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progress; things will change without warning. The [issues list](https://github.com/elves/elvish/issues) contains many things I'm working on.
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## Screenshot
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Elvish looks like this:
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## Prebuilt binaries
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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).
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## Getting Started
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Put your startup script in `~/.elvish/rc.elv`.
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Elvish mimics bash and zsh in a lot of places. The following shows some key differences and highlights, as well as some common tasks:
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* Define aliases like `fn ls { external:ls --color $@ }`
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* Press Up to search through history. It uses what you have typed to do prefix match. To cancel, press Escape.
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* Press Tab to start completion. Use arrow key and Tab to select the candidate; press Enter, or just continue typing to accept. To cancel, press Enter.
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* Press Ctrl-N to start navigation mode. Press Ctrl-H to show hidden files; press again to hide. Likewise, pressing Escape gets you back to the default (insert) mode.
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* Try typing `echo [` and press Enter. Elvish knows that the command is unfinished due to the unclosed `[` and inserts a newline instead of accepting the command. Moreover, common errors like syntax errors and missing variables are highlighted in real time.
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* Elvish remembers which directories you have visisted. Use `dirs` to show the history. `jump x` jumps to the highest-scored directory containing `x`.
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* Lists look like `[a b c]`, and maps look like `[&key1=value1 &key2=value2]`. Unlike other shells, lists never expands to multiple words, unless you explicitly splice it by prefixing the variable name with `$@`:
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```sh
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~> li=[1 2 3]
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~> for x in $li; do echo $x; done
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[1 2 3]
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~> for x in $@li; do echo $x; done
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1
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2
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3
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```
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* You can manipulate search paths through the special list `$paths`:
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```sh
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~> echo $paths
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[/bin /sbin]
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~> paths=[/opt/bin $@paths /usr/bin]
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~> echo $paths
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[/opt/bin /bin /sbin /usr/bin]
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~> echo $env:PATH
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/opt/bin:/bin:/sbin:/usr/bin
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```
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* You can manipulate the keybinding through the map `$le:binding`. For example, this binds Ctrl-L to clearing the terminal: `le:binding[insert][Ctrl-L]={ clear > /dev/tty }`. The first index is the mode and the second is the key. (Yes, the braces enclose a lambda.)
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Use `put $le:binding` to get a nice (albeit long) view of the current keybinding.
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* Environment variables live in a separate `env:` namespace and must be explicitly qualified:
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```sh
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~> put $env:HOME
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▶ /home/xiaq
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~> env:PATH=$env:PATH":/bin"
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```
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* There is no interpolation inside double quotes (yet). Use implicit string concatenation:
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```sh
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~> name=xiaq
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~> echo "My name is "$name"."
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My name is xiaq.
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```
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* Elementary floating-point arithmetics as well as comparisons are builtin. Unfortunately, you have to use prefix notation:
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```sh
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~> + 1 2
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▶ 3
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~> div `mul 2 3` 4 # div for /, mul for *
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▶ 1.5
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~> div (mul 2 3) 4 # parentheses are equivalent to backquotes, but look nicer in arithmetics
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▶ 1.5
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~> gt 1 2 # gt for >
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false
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~> lt 1 2 # lt for <; silence means "true"
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```
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* Functions are defined with `fn`. You can name arguments:
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```sh
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~> fn square [x]{
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mul $x $x
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}
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~> square 4
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▶ 16
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```
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* Output of some builtin commands start with a funny "▶". It is not part of the output itself, but shows that such commands output a stream of values instead of bytes. As such, their internal structures as well as boundaries between valued are preserved. This allows us to manipulate structured data in the shell; more on this later.
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## More Screenshots:
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Tab completion:
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Navigation mode:
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## Building Elvish
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Go >= 1.5 is required. Linux is fully supported. It is likely to work on BSDs and Mac OS X. Windows is **not** supported yet.
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The main binary can be installed using `go get github.com/elves/elvish`. There is also an auxiliary program called elvish-stub; install it with `make stub`. Elvish is funtional without the stub, but job control features depend on it.
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If you are lazy and use `bash` for `zsh` now, here is something you can copy-paste into your terminal:
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```sh
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export GOPATH=$HOME/go
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export PATH=$PATH:$GOPATH/bin
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mkdir -p $GOPATH
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go get github.com/elves/elvish
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make -C $GOPATH/src/github.com/elves/elvish stub
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for f in ~/.bashrc ~/.zshrc; do
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echo -e 'export GOPATH=$HOME/go\nexport PATH=$PATH:$GOPATH/bin' >> $f
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done
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```
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[How To Write Go Code](http://golang.org/doc/code.html) explains how `$GOPATH` works.
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## Name
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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.
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The adjective for elvish is also "elvish", not "elvishy" and definitely not "elvishish".
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## Test coverages:
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|Package|Coverage|
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|-------|--------|
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|edit|[](https://gocover.io/github.com/elves/elvish/edit/)|
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|eval|[](https://gocover.io/github.com/elves/elvish/eval/)|
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|glob|[](https://gocover.io/github.com/elves/elvish/glob/)|
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|parse|[](https://gocover.io/github.com/elves/elvish/parse/)|
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|run|[](https://gocover.io/github.com/elves/elvish/run/)|
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|store|[](https://gocover.io/github.com/elves/elvish/store/)|
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|stub|[](https://gocover.io/github.com/elves/elvish/stub/)|
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|sys|[](https://gocover.io/github.com/elves/elvish/sys/)|
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|util|[](https://gocover.io/github.com/elves/elvish/util/)|
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