Adds a user to OS X (Yosemite and later), sets the machine as "Setup Done" and skips iCloud registration for the created user.

add_user

#!/bin/bash
# Adds a user via command line, and sets the machine as "Setup Done"

# Ensure that it runs as root
if [ "$(id -u)" != "0" ]; then
    echo "${0} must be run as root, or using sudo"
    exit 1
fi

if [ -n "${1}" -a -n "${2}" -a -n "${3}" -a -n "${4}" ]; then
    echo "Using parameters from command line:"
    echo "    USERNAME: ${1}"
    echo "    FULLNAME: ${2}"
    echo "    PASSWORD: ****"
    echo "    EXTRA_GROUPS: ${4}"
elif [ -n "${1}" -o -n "${2}" -o -n "${3}" -o -n "${4}" ]; then
    echo "Usage: ${0} [<USERNAME> <FULLNAME> <PASSWORD> <EXTRA_GROUPS>]"
    exit 1
fi

# Lower-cases a string
function to_lower { echo "${1}" | tr '[:upper:]' '[:lower:]'; }

# Required information
echo "Creating a new user..."
USERNAME="${1}"
while [ -z "${USERNAME}" ]; do
    echo -n "Username: "
    read USERNAME
    USERNAME="$(to_lower "${USERNAME}")"
    if [ -n "${USERNAME}" -a -d "/Users/${USERNAME}" ]; then
        echo "Username '${USERNAME}' already exists"
        USERNAME=""
    fi
done

FULLNAME="${2}"
while [ -z "${FULLNAME}" ]; do
    echo -n "Full name: "
    read FULLNAME
done

PASSWORD="${3}"
while [ -z "${PASSWORD}" ]; do
    echo -n "Password: "
    read -s PASSWD1
    echo ""
    echo -n "Retype password: "
    read -s PASSWD2
    echo ""
    if [ "${PASSWD1}" == "${PASSWD2}" ]; then
        PASSWORD="${PASSWD1}"
    else
        echo "Passwords do not match"
    fi
done

EXTRA_GROUPS="${4}"
while [ -z "${EXTRA_GROUPS}" ]; do
    echo -n "Is this an administrative user? (y/n) "
    read ADMIN
    ADMIN="$(to_lower "${ADMIN}")"

    if [ "${ADMIN}" == "y" ]; then
        EXTRA_GROUPS="admin"
    elif [ "${ADMIN}" == "n" ]; then
        EXTRA_GROUPS="staff"
    else
        echo "Please enter 'y' or 'n'"
    fi
done

# Create a UID that is not currently in use
echo "Creating an unused UID for new user..."
MAXID=$(dscl . -list /Users UniqueID | awk '{print $2}' | sort -ug | tail -1)
if [ ${MAXID} -lt 500 ]; then MAXID=500; fi
USERID=$((MAXID+1))

# Create the user account by running dscl
echo "Creating necessary files..."
dscl . -create /Users/${USERNAME}
dscl . -create /Users/${USERNAME} UserShell /bin/bash
dscl . -create /Users/${USERNAME} RealName "${FULLNAME}"
dscl . -create /Users/${USERNAME} UniqueID "${USERID}"
dscl . -create /Users/${USERNAME} PrimaryGroupID 20
dscl . -create /Users/${USERNAME} NFSHomeDirectory /Users/${USERNAME}
dscl . -passwd /Users/${USERNAME} ${PASSWORD}

# Add user to any specified groups
echo "Adding user to specified groups..."
for GROUP in ${EXTRA_GROUPS} ; do
    dseditgroup -o edit -t user -a ${USERNAME} ${GROUP}
    if [ "${GROUP}" == "admin" -a ! -f "/var/db/.AppleSetupDone" ]; then
        touch /var/db/.AppleSetupDone
    fi
done

# Create the home directory
echo "Creating home directory..."
createhomedir -c 2>&1 | grep -v "shell-init"

# Patch to not prompt for iCloud
PDIR="/Users/${USERNAME}/Library/Preferences"
SUP="${PDIR}/com.apple.SetupAssistant"
[ -d "${PDIR}" ] || { sudo -u ${USERNAME} -- mkdir -p "${PDIR}"; }
defaults write "${SUP}" DidSeeCloudSetup -bool TRUE
defaults write "${SUP}" GestureMovieSeen none
defaults write "${SUP}" LastSeenCloudProductVersion "$(sw_vers -productVersion)"
chown ${USERNAME}:staff "${SUP}.plist"

echo "Created user #${USERID}: ${USERNAME} (${FULLNAME})"