Create user account from the OS X command line

Here is a procedure for adding a new user in OS X from the command line.
The problem is that there is no useradd or adduser in OS X, so the user must
be added to the Directory Service by hand.

1. First make sure to find an unused uid (unique ID) for the user,
   dscl . -list /Users UniqueID
   will list all the existing users, an unused number above 500 is good.
   
   In general to list a property from the directory use:
   dscl . -list {users|groups} {u|g}id
   or to see the id's of an existing user use:
   id auser
   
   
2. The Add the directory entry:
   dscl . -create /Users/luser
   dscl . -create /Users/luser UserShell /bin/bash
   dscl . -create /Users/luser RealName "Lucius Q. User"
   dscl . -create /Users/luser UniqueID "503"
   dscl . -create /Users/luser PrimaryGroupID 20
   dscl . -create /Users/luser NFSHomeDirectory /Users/luser
   
   The PrimaryGroupID=20 is usually staff. 80 is admin, it can be added with:
   dscl . -append /Groups/admin GroupMembership luser
   
   
3. Set the password:
   dscl . -passwd /Users/luser password
   or
   passwd luser
   
   
4. Finally, create the home directory with the appropriate permissions:
   mkdir /Users/luser
   chown luser:staff luser
   or even better, create and populate the directory with
   createhomedir -c -u luser
   
   
   
   

Further reading: http://serverfault.com/questions/20702/how-do-i-create-user-accounts-from-the-terminal-in-mac-os-x-10-5