Nushell Documentation

Nushell is a modern, cross-platform shell that combines the Unix philosophy of piping simple commands together with the features of a rich programming language. Unlike traditional shells, Nushell works directly with structured data rather than just raw text strings.

Key focus areas include:

• Flexible cross-platform shell: A modern feel across different operating systems.
• Structured data processing: Solving problems using a programming language designed to work with the structure of your data.
• Developer experience: Providing clear error messages and clean IDE support.

Nushell is a new type of shell designed around structured data and type safety.

• Everything is data: Nu pipelines use structured data, allowing you to safely select, filter, and sort data without manual string parsing.
• Native Data Support: Nu supports formats like JSON, YAML, SQLite, and Excel out of the box.
• Type Safety: Nu operates on typed data, which helps catch bugs and provides detailed error messages indicating exactly where and why a failure occurred.
• Extensibility: Nu features a powerful plugin system for easy extension.

Nushell 0.98.0 introduced several significant changes to error handling, evaluation, and parsing:

• Error Handling: Non-zero exit codes are now treated as errors. Core dump errors are always printed, and SIGPIPE no longer triggers an error. Other signal termination message printing is controlled by a specific setting.
• Evaluator: The Intermediate Representation (IR) evaluator is now the default.
• Clipboard: Support for the system clipboard has been removed.
• Record Parsing: Changes were made to how records are parsed, specifically relaxing the requirement for parentheses in certain contexts.
• Plugins: Switched from bincode to MessagePack for plugin custom values.

Nushell 0.84.0 introduced several key improvements:

• Constants from modules: You can now access constants defined within modules.
• Compact table display: New options are available for more compact table rendering.
• Consistent format ... commands: Improvements to the consistency of formatting commands.
• scope command enhancements: Updates to how scope is handled and inspected.
• Improved http commands: Better handling of HTTP headers.
• Dataframe features: Ongoing work on optional dataframe capabilities.
• Command organization: Refined organization of commands within the shell.

The plugin command is a built-in command used to manage the lifecycle of NuShell plugins, including adding them to the registry, loading them into the current scope, and listing or removing them.

Note that plugin use is a keyword used to load a plugin from the registry into your current session, whereas other subcommands manage the registry or the running state of the plugin.

# Example workflow
plugin add nu_plugin_inc
plugin use inc

Nushell 0.76 introduced several key improvements to language syntax, command organization, and error handling:

• String and List Multiplication: You can now use the multiplication operator (*) to repeat strings and lists.
• Command Separation: Dataframe commands are now explicitly separated from core Nushell commands.
• Case Sensitivity: Clarification/changes regarding PATH vs Path usage.
• Plugin Improvements: More commands have been moved to the plugin system, and plugins now receive first-class help support.
• Improved Error Messages: Enhanced error reporting for:
  • int and string literals
  • Invalid 2-character escapes
  • Invalid unicode escapes

The spread operator (...) allows you to unpack the elements of a list or the key-value pairs of a record into a new list or record literal. This is useful for avoiding explicit append or merge calls.

Rules:

• There must be no whitespace between the ... and the expression being spread.
• You can spread variables, subexpressions, and literals.
• Currently, spreading arguments to commands is not yet implemented.

# Spreading in lists
let list = ["foo"]
[
    1,
    ...$list,
    ...("foo" | split chars),
    ...[3 9],
    []
]

# Spreading in records
let record = { a: "foo" }
{
    ...$record,
    y: "bar",
    ...{ z: 2 }
}

Nushell now enforces stricter rules to prevent the modification of special environment variables controlled by the system.

Prohibited Variables

You can no longer change the following special environment variables via $env.VAR_NAME assignment, with-env, the FOO=bar command shorthand, or load-env:

• $env.PWD
• $env.FILE_PWD
• $env.CURRENT_FILE

Shorthand Syntax Restrictions

The FOO=bar BAZ=bla command shorthand syntax no longer allows repeating the same environment variable name. Doing so will now raise an error.

# Now raises an error
FOO=bar FOO=bla command