cargo-shell

Table of Contents

• Introduction
• Installation
• Usage
• Is that…​it?
  • cargo-watch integration
  • Running a command using a different toolchain
  • Running a command under multiple toolchains
  • Running a list of commands from a file
  • Changing the prompt mid-session
• Configuration
  • Prompt
  • Default toolchain
  • Toolchain list
• TODO

Introduction

cargo shell is a command shell for cargo, inspired by sbt. It incorporates a number of existing tools, along with some additional features, to make developing rust applications a little nicer.

Installation

cargo-shell makes liberal use of the tools you probably already have installed, so it expects that you have a working rust installation (obviously) as well as rustup.rs.

$ cargo install cargo-shell

Usage

After installation, the shell can be started by running cargo shell on the command line:

$ cargo shell
Welcome to cargo-shell v0.1.0
>> build
>> test
>> bench

…​etc

Is that…​it?

At this point, we don’t really have a lot of advantages over just aliasing cargo to c and running c build, etc. However, cargo-shell comes with a few built-in features that make it more useful.

cargo-watch integration

If you have cargo-watch installed on your system, you can cause any command to be re-run when the source files change. This is done by prepending a ~ to the command:

$ cargo shell
Welcome to cargo-shell v0.1.0
>> ~run
Hello, World!
Waiting for changes... Hit Ctrl-C to stop.

Running a command using a different toolchain

rustup is great for letting us run commands using different versions of rust. The command to do this, however, can get a bit verbose. Sure, aliases can help. But with the command shell, running a command with a different toolchain is simple:

Let’s say you are using the stable toolchain, but want to test using nightly:

$ cargo shell
Welcome to cargo-shell v0.1.0
>> build
   # builds using `stable`
>> ++nightly test
   # tests using `nightly`

After the cargo test command is done running, the shell will go back to using the stable toolchain again. To permanently change it in the shell, just leave the command off the end:

$ cargo shell
Welcome to cargo-shell v0.1.0
>> ++nightly
>> do build, test
   # shell remains in nightly until you change it back manually

Running a command under multiple toolchains

Let’s say we want to run the tests for a project under stable, beta, and nightly (which are the default, though this is configurable):

$ cargo shell
Welcome to cargo-shell v0.1.0
>> +test

…​and that’s it! There is a config option, cargo-shell.toolchains that will let you customize the list of toolchains that this runs.

Running a list of commands from a file

The < operator will let you run a series of commands from a file. For example, this file:

test-file

build
test
bench

Can be run like this:

$ cargo shell
Welcome to cargo-shell v0.1.0
>> < test-file

and the build, test and bench commands will be run in sequence

Changing the prompt mid-session

The prompt can be changed permanently in your config, but if you want to change it mid-session, you can use the p command:

$ cargo shell
Welcome to cargo-shell v0.1.0
>> p $
$

One limitation is that leading & trailing whitespace is trimmed, so if you want a space at the end of your prompt, use quotes:

$ cargo shell
Welcome to cargo-shell v0.1.0
>> p "$ "
$ # now there is a space here

Configuration

There are a few configuration options available to customize cargo-shell. You put them in a .cargo/config file under the [cargo-shell] heading.

Prompt

This will customize the look of the shell prompt. There are a few placeholders that you can use: {project}, {version} and {toolchain}. After every command, cargo-shell will replace them with the project name, project version, and current toolchain, respectively.

For example, to end up with a prompt like "my-project stable>> ", you would set the prompt to this:

[cargo-shell]
prompt = "{project} {toolchain}>> "

By default it is just:

[cargo-shell]
prompt = ">> "

Default toolchain

This is the toolchain that the shell will start using by default.

Note	This will be going away as soon as I get better integration with rustup’s overrides in place. At that point, cargo-shell will use the same default toolchain as rustup, and will respect any overrides that you have put in place using rustup.

[cargo-shell]
default_toolchain = "stable"

Toolchain list

This will customize the toolchains that a command is run under when using the + shell command.

[cargo-shell]
toolchains = ["stable", "beta", "nightly"]

TODO

• ✓ Documentation

• ❏ Detect toolchain default & overrides from rustup

• ❏ Shell history

• ❏ git integration for the prompt

• ❏ autocomplete