A Nu-er Shell

03 October 2024

Updated: 04 October 2024

Take a look at Nushell

ZOOOOOOM!

Is everything big enough and are we in dark mode?

Nushell

Go to demo

Nushell is a shell that makes use of the Nu Programming Language

  • Cross-platform
  • Everything is data
  • Extensible
  • Composition based
  • Strongly typed

Data

  • Traditional shells, e.g. bash, treat everything as strings
  • Nushell treats input streams as data that can be transformed
  • Uses the Nu Language for transforming data
  • Wraps common commands into data-rich ones, e.g. ls, open
Terminal window
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> ls
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╭───┬─────────────┬──────┬───────────┬────────────────╮
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│ # │    name     │ type │   size    │    modified    │
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├───┼─────────────┼──────┼───────────┼────────────────┤
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│ 0 │ config.nu   │ file │   1.000 B │ a month ago    │
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│ 1 │ env.nu      │ file │   4.3 KiB │ a month ago    │
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│ 2 │ history.txt │ file │ 193.6 KiB │ 12 minutes ago │
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│ 3 │ scripts     │ dir  │     256 B │ 2 months ago   │
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╰───┴─────────────┴──────┴───────────┴────────────────╯

Pipelines

  • A functional programming technique
  • Feels a bit like LINQ
  • Can be chained together and composed
Terminal window
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git log --oneline | lines | parse $template
  • Lots of builtin function, e.g. lines, parse, map, where, find, filter, each, glob, watch … and more!

File Formats

  • Supports many common file formats as data
    • CSV
    • JSON
    • YAML
  • Can add support for custom formats easily
  • Easily convert between simple formats
Terminal window
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open data.csv | to json | save data.json

The Nu Language

Terminal window
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# compose with command utilities
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let contents = cat my-file.txt
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print $contents
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# define custom functions/commands
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def "my custom command" [name:string] {
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    "Hello " + $name
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}
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# use a module
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use my_module.nu
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# load a source file into scope
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source my_file.nu
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# create an alias
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alias gito = git log --oneline

Demo

Examples below

Nushell

  • Supports pretty much anything available in a file
  • Easily configurable - $nu.config-path

Show my setup

Examples

Terminal window
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const url = 'https://dummyjson.com/todos'
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# This is the main method, running --help will show docs for all subcommands
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def example [] {
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    print "Working with HTTP Data"
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}
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def "example get_full" [] {
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    http get $url --full
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}
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def "example filter_todos" [] {
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    http get $url
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        | get todos
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        | where completed == false
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        | select id todo userId
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        | to yaml
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}
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let template = '{ip} - - [{date}] "{method} {url} {protocol}" {status} {size} "{served}" "{useragent}"'
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let logs = "https://raw.githubusercontent.com/elastic/examples/refs/heads/master/Common%20Data%20Formats/apache_logs/apache_logs"
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def "example download_logs" [] {
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    http get $logs
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        | save http-logs.txt
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}
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def "example parse_logs" [] {
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    open http-logs.txt
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        | lines
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        | parse $template
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}
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def "example filter_logs" [] {
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    example parse_logs
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        | where method == POST
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        | select url status useragent
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}
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def "example filter_pngs" [] {
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    example parse_logs
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        | where method == GET
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        | where url =~ ".png"
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        | where size != "-"
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        | into int size
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        | where size > 500_000
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        | select url status served size
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}
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def "example live_convert" [] {
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    watch input.csv { open input.csv | to json | save output.yaml }
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}
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alias helpme = example --help