Nushell

Terminal shell, like bash or zsh

Pros 👍

• Do math anytime. The < & > do mean “less than” and “greater than”, instead of “read from file” and “write to file”

• Type safety

• Rich type system (even has records)

• The way you specify completions for third-party commands looks awesome: https://www.nushell.sh/book/externs.html

  Like sourcing this just works (no need for special completion registration):

  def kubectl-contexts [] {
  	open ~/.kube/config | from yaml | get contexts.name
  }
  
  def kubectl-resources [] {
  	kubectl api-resources -o name | lines
  }
  
  def kubectl-namespaces [] {
  	kubectl get ns -o name | lines | split column '/' | get column2
  }
  
  def kubectl-outputs [] {
  	"json|yaml|name|go-template|go-template-file|template|templatefile|jsonpath|jsonpath-as-json|jsonpath-file|custom-columns|custom-columns-file|wide" \
        | split row '|'
  }
  
  export extern "kubectl get" [
  	resource: string@kubectl-resources          # name of Kubernetes resource
  	--namespace(-n): string@kubectl-namespaces  # show resources from specific Kubernetes namespace
  	--all-namespaces(-A)                        # show resources all Kubernetes namespaces
  	--context: string                           # context from your ~/.kube/config
  	--output(-o): string@kubectl-outputs        # output format
  ]

  It even validates it for me:

  $ kubectl get -o wide
  Error: nu::parser::missing_positional
  
    × Missing required positional argument.
     ╭─[entry #86:1:1]
   1 │ kubectl get -o wide
     ·            ▲
     ·            ╰── missing resource
     ╰────
    help: Usage: kubectl get {flags} <resource>

Cons 👎

• Quite verbose. E.g:
  • ls */ vs ls | where type == dir
  • cat file vs open --raw file
  • echo foo >> file vs "foo" | save --raw --append file
• No dir aliasing (like if I in zsh run hash -d c=~/code, then I can do ~c/foo to go to ~/code/foo)
• Can’t parse table output.
• Can’t really deal with streaming data, such as kubectl get pods -w | lines
• Can’t Ctrl+Z an application, but instead must install third party tool pueued for this?
• Too unknown. Completion support for random CLI apps:
  • bash: super common
  • zsh: quite common (zsh can load bash completions anyway)
  • fish: uncommon
  • powershell: uncommon
  • nushell: non-existent
• Completions dont work for aliases (for now: https://github.com/nushell/nushell/issues/8483)