nushell

name	nushell
description	Process structured data in pipelines, filter tables, transform JSON/CSV/YAML, and define custom commands. Use when scripting with typed parameters or working with tabular data.

nu-shell

Structured-data shell. Pipelines work on tables, lists, and records, not only text.

Core Concepts

Data Types

• Record: { name: "John", age: 30 }
• List: [1, 2, 3]
• Table: list of records with same fields

Pipelines

ls | where size > 10mb | sort-by size

Running Scripts

nu myscript.nu           # Run script file
nu -c 'ls | length'      # Run inline command
source myscript.nu       # Run in current session

Data Manipulation

Loading and Saving

let config = (open config.json)
let data = (open data.csv)

$data | save output.yaml
$data | to json | save output.json

Filtering and Selecting

ls | where name =~ "test"        # Filter rows
ls | select name size            # Select columns
(open package.json).version      # Access fields

Processing Tables

ls | where size > 10mb           # Filter by condition
ls | select name size            # Select columns
ls | sort-by size                # Sort
ls | group-by name               # Group
ls | length                      # Count rows

Processing Records

let user = { name: "John", age: 30 }
echo $user.name                  # Access field

let updated = { ...$user, age: 31 }  # Update field
let merged = { ...$config, debug: true }  # Merge

Processing Lists

[1, 2, 3, 4, 5] | where $it > 2           # Filter
[1, 2, 3] | each { |x| $x * 2 }           # Map
[1, 2, 3, 4, 5] | reduce { |acc, x| $acc + $x }  # Reduce

Scripting

Basic Script Structure

#!/usr/bin/env nu

def "my command" [param: string] {
    echo $"Hello, ($param)"
}

my command "world"

Control Flow

# If statement
if true { echo "Hello" }

# If-else
if true { echo "Yes" } else { echo "No" }

# For loop
for i in 1..10 { echo $i }

# While loop
mut i = 1
while $i <= 10 {
    echo $i
    $i = $i + 1
}

Custom Commands

# With typed parameters
def "create project" [name: string, type: string = "typescript"] {
    echo $"Creating ($name) with ($type)"
}

# With flags
def "deploy" [--env: string = "production"] {
    echo $"Deploying to ($env)"
}

File Operations

let content = (open "file.txt")       # Read
$content | save "output.txt"          # Write
$content | save --append "file.txt"   # Append

Tips

• Use nu -c 'command' for inline runs
• Use open to load many data formats
• Use save to write many data formats
• Use where to filter tables
• Use select to pick columns
• Use sort-by to sort tables
• Use each to map lists
• Use reduce to combine list items
• Use def for custom commands with typed params
• Use ... to merge records