Nash

Nash is a command-line editor for bash and compatible shells. It handles user input to provide a better user experience, and when the user hits the Enter key, it simply passes the command to bash for processing.

Nash is implemented in JavaScript and focuses on:

• Providing great UX and productivity to the command-line.
• Being highly extensible and customizable.
• Bringing shell power to JavaScript developers. Shells such as zsh or fish are greatly configurable, but customizing them requires writing shell script code, which (for JS developers) is not as user-friendly as JavaScript. Extensions are written much faster in JS, and are easier to understand by the common developer.

Quick links

• If you want to see how nash looks like, check some screenshots.
• Check the user manual for a detailed description of nash functions.

Main features

• Flexible prompt, configurable by settings and by JavaScript code.
• Powerful command history navigation:
  • The up and down keys navigate the history, showing only the entries that start with the current line.
  • The page up key displays a menu with all history lines that start with the current line.
• Directory history navigation: the page down key displays a menu with the most recently visited directories, showing only the entries that contain the text in the current line.
• Interactive tab-completion: pressing tab completes a file name, but if multiple matching files are available, a menu is displayed, letting the user navigate and select the file name. Completion supports other elements such as directories, command options and environment variables, and displays file information or option documentation depending on the case.
• All menus (command history, directory history and tab-completion) allow typing more characters to narrow the search.
• Syntax highlight, clearly coloring the different parts of a command, and warning of potential errors.
• History suggestions: when typing a command, if the text matches a previous command, the remaining text is displayed in grey, letting the user immediately complete the command.
• All these features are also available when establishing a connection with a remote system, even if nash is not installed in the remote system: only bash is required. This is especially useful when:
  • Accessing restricted systems where installing nash is not easy or even not possible.
  • Accessing small or short-lived environments, such as a docker container.
• Configurable color palette. Colors can be configured by name (e.g. "red", "gren", etc.) or by RGB hex as in CSS (e.g. #a6e22e).
• Configuration and extensions are implemented as plain JavaScript code, centered around the ~/.nash/nashrc.js file, which is loaded during startup. Example configuration and extensions are provided in the ~/.nash directory, which is populated when nash is started for the first time. For instance:
  • Color settings are configured via JSON - you can make your terminal use the same color palette as your code editor. Most terminals support 16 million colors, and although this feature is initially disabled in ~/.nash/nashrc.js to ensure compatibility, it is really worth trying enabling it by uncommenting the line containing trueColor: true near the end of the file.
  • Keyboard shortcuts are reassigned using the bindKey API - the example in ~/.nash/custom-keys.js illustrates how to do it. The F1 key displays the list of keyboard shortcuts, and ctrl-k displays the name of any key combination.
  • Completion helpers for known commands (git, docker, npm, etc.) are configured via JSON settings.
• An extensible plugin system which facilitates the addition of features.

Check the ToDo for a list of features under development and planned for the future. Suggestions are welcome.

Installation

If after a successful installation you get strange behavior, see Starting nash for troubleshooting. Also, check the Recommended prerequisites section below.

If you have node and npm installed

As usual:

$ npm install -g bnash  # the "nash" name was taken in npm ¯\_(ツ)_/¯

Then just type bnash to launch it.

If you get installation errors containing node-gyp in the error messages, this is because you need to install the native build tools first. That installation depends on the OS - for example, for Ubuntu the following command installs those prerequisites:

$ sudo apt-get install build-essential

You can get more details in the node-gyp installation document.

...Or you can just download the binary installation: see the next section.

Binary installation

The releases page contains binary packages for Linux and MacOS. You can download the appropriate nash-[version]-[platform].tar.gz file, then unpack it into a directory of your choice. For example:

$ mkdir ~/nash-inst
$ cd ~/nash-inst
$ # Use the appropirate link for nash-[version]-[platform].tar.gz
$ curl -OL https://github.com/lcrespom/nash/releases/download/1.10.1/nash-1.10.1-linux.tar.gz
$ tar -xzf nash-1.10.1-linux.tar.gz

Finally, to run nash:

$ ./nash

To easily launch nash in the future, you can copy the extracted files somewhere in your $PATH. An appropriate place is /usr/local/bin:

$ sudo cp nash pty.node /usr/local/bin

From then on, you can simply launch it by typing nash.

The binary distribution packages nash code along with the node.js runtime in a single executable, except for the pty.node file, which must be placed alongside. The packaging is done using the great pkg tool.

From source code

If you want to run nash from the source code (and maybe help with development), just clone the repo and type npm install. Then, to open a shell, type node src/nash.

$ git clone https://github.com/lcrespom/nash.git
$ npm install
$ node src/nash

Windows

There is no direct Windows support, but an Ubuntu terminal can be installed in windows very easily through the Microsoft Store. See instructions here.

Recommended prerequisites

In order to get the best experience from nash, the following prerequisites are recommended:

Powerline fonts

A collection of fonts that are optimized for the terminal and contain useful symbol characters, e.g. for displaying a fancy prompt, git repository symbol, etc. They can be downloaded form here.

Once the terminal is configured to use a powerline font, add the following entry in the exported options of .nash/nashrc.js:

   prompt: { powerFont: true }

This will tell the prompt plugin that it can use fancy symbol characters, e.g. for the git status.

A good terminal app

The default terminal application that comes preinstalled with the OS is usually quite limited, and may even cause defective output or glitches when nash tries to generate colorful output. The recommended alternatives are the following:

• Mac: iTerm2. Although the default terminal is quite powerful, it does not support 16 million colorws (see below).
• Windows:
  • Windows Terminal. The GitHub page contains instructions for different installation methods, and at the very beginning of the README.md there is a link to the app in the Microsoft Store, which is the easiest installation method.
  • The terminal provided by the Ubuntu WSL app is also quite decent.
• Linux: most Linux distributions come with a powerful terminal by default.

Once you are using a good terminal app, make sure you enable 16 million color support by uncommenting the line trueColor: true in the options of .nash/nashrc.js. Some pugins make use of this feature, but it is disabled by default because there is no safe way to detect 16 million color support, and attempting to use this feature on a terminal that does not support it results in unreadable output.

Related projects

If you are thinking about using JavaScript to implement your shell scripts, check out ShellJS.

If you are looking for a full shell interpreter with good UX, check out Oh My Zsh and Fish Shell.