ssh_user.rb

#!/usr/bin/env ruby

CHARACTERS = (('A'..'Z').to_a + ('a'..'z').to_a + (0..9).to_a)
GROUP = 53

def ridiculous_password
  (1..20).map do
    CHARACTERS[rand(CHARACTERS.length)]
  end.join
end

def create_ssh_user(username)
  `dscl . -create /Users/#{username}`
  `dscl . -create /Users/#{username} UserShell /bin/bash`
  `dscl . -create /Users/#{username} RealName "#{username}"`
  `dscl . -create /Users/#{username} UniqueID #{rand(100_000)}`
  `dscl . -create /Users/#{username} PrimaryGroupID #{GROUP}` #console users
  `dscl . -create /Users/#{username} NFSHomeDirectory /Users/#{username}`
  `mkdir -p /Users/#{username}/.ssh`
  `dscl . -passwd /Users/#{username} #{ridiculous_password}`
end

def delete_user(username)
  `rm -rf /Users/#{username}`
  `dscl . -delete /Users/#{username}`
end

username = ARGV.shift
pub_key_filepath = ARGV.shift
user_path = "/Users/#{username}"

create_ssh_user username

`cp #{pub_key_filepath} #{user_path}/.ssh`

`cat #{pub_key_filepath} > #{user_path}/.ssh/authorized_keys`

`chown -R #{username} #{user_path}`
`chgrp -R #{GROUP} #{user_path}`