[ruby] How to check if a given directory exists in Ruby

I am trying to write a script which automatically checks out or updates a Subversion URL based on whether a specified directory exists or not.

For some reason, my code isn't working and always returns true even if it's false:

def directory_exists?(directory)
  return false if Dir[directory] == nil
  true
end

What am I doing wrong?

File.exist?("directory")

Dir[] returns an array, so it will never be nil. If you want to do it your way, you could do

Dir["directory"].empty?

which will return true if it wasn't found.

You could use Kernel#test:

test ?d, 'some directory'

it gets it's origins from https://ss64.com/bash/test.html you will notice bash test has this flag -d to test if a directory exists -d file True if file is a Directory. [[ -d demofile ]]

You can also use Dir::exist? like so:

Dir.exist?('Directory Name')

Returns true if the 'Directory Name' is a directory, false otherwise.¹

All the other answers are correct, however, you might have problems if you're trying to check directory in a user's home directory. Make sure you expand the relative path before checking:

File.exists? '~/exists'
=> false
File.directory? '~/exists'
=> false
File.exists? File.expand_path('~/exists')
=> true