nu-shell

Structured data scripting through pipelines with tables, lists, and records.

Core Concepts

Data Types

• Record: { name: "John", age: 30 }

• List: [1, 2, 3]

• Table: A list of records with the same keys

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' to run commands inline

• Use open to load data from various formats

• Use save to write data to various formats

• Use where to filter tables

• Use select to choose columns

• Use sort-by to sort tables

• Use each to map over lists

• Use reduce to combine list elements