Create a user from the command line on Mac OS X

create_user.sh

#!/bin/bash

# This must be run as root. Needs to ask for password interactively and get the next unique
# user ID automatically, but you get the idea.

USERNAME='username'
USER_ID=510
DISPLAY_NAME='User Name'
PASSWORD='password'

dscl . -create /Users/${USERNAME}
dscl . -create /Users/${USERNAME} UserShell /bin/bash
dscl . -create /Users/${USERNAME} RealName "${DISPLAY_NAME}"
dscl . -create /Users/${USERNAME} UniqueID ${USER_ID}
dscl . -create /Users/${USERNAME} PrimaryGroupID 1000
dscl . -create /Users/${USERNAME} NFSHomeDirectory /Local/Users/${USERNAME}
dscl . -passwd /Users/${USERNAME} ${PASSWORD}

# If you need to make this user an administrator, do:
dscl . -append /Groups/admin GroupMembership ${USERNAME}