How do I check if a directory exists in a Nushell script?

I would like to know how I check if a directory exists in Nushell?

If you just need to confirm that a directory exists, you can use the path exists builtin. If you need to make sure that it is a directory (rather than a file), see the custom command path is-directory below:

path exists

Examples:

"/home" | path exists
# => true

"MRE" | path exists
# => false

"./nu-0.71.0-x86_64-unknown-linux-gnu" | path exists
# => true

[ '.', '/home', 'MRE'] | path exists
# => ╭───┬───────╮
# => │ 0 │ true  │
# => │ 1 │ true  │
# => │ 2 │ false │
# => ╰───┴───────╯

[ '.', '/home', 'MRE'] | all {path exists}
# => false

[ '.', '/home', 'MRE'] | any {path exists}
# => true

if ([ '.', '/home', '/proc'] | all {path exists}) {
    "All directories exists"
} else {
    "One or more directories are missing"
}
# => All directories exists

^{(^Thanks to @Raze for the simplification using all.)}

See help path exists for more details and help path for more path helper builtins.

path is-directory

The following custom command should both confirm that the path exists and that it is a directory:

def "path is-directory" [] {
  let type = ( describe -d | get type)
  let input = $in
  match $type {
    string => {
      try {
        let filetype = ls -D $input | get type.0
        $filetype == dir
      } 
      | default false
    }

    list => {
      $input | each { path is-directory }
    }

    _ => { error make { msg: "Only accepts string or list" }}
  }
}

The same examples above can then be used with this command. For instance:

[ '.', '/usr/bin/ls', '/home', 'MRE'] | path is-directory
# => ╭───┬───────╮
# => │ 0 │ true  │
# => │ 1 │ false │
# => │ 2 │ true  │
# => │ 3 │ false │
# => ╰───┴───────╯